Method and apparatus for system information acquisition in wireless communication system

ABSTRACT

The present disclosure relates to a pre-5th-generation (5G) or 5G communication system to be provided for supporting higher data rates beyond 4th-generation (4G) communication system such as long term evolution (LTE). Next generation of wireless cellular operation is expected to be deployed in higher frequency above 6 GHz (eg. 10 GHz˜100 GHz, also called mmWave and/or cmWave) due to availability of large amount of spectrum bandwidths. The physical layer of wireless cellular system in both DL and UL operating in mmWave/cmWave would be based on new air-interface different from that of LTE-A air-interface because the radio characteristics is different for mmWave/cmWave bands. The wireless system deployed in mmWave/cmWave system is expected to employ DL beam sweeping on broadcast control information to provide cell coverage to the UE which would result in excessive signaling overhead.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 U.S.C. § 119(a) of anIndian Provisional patent application filed in the Indian Patent Officeon Oct. 16, 2015 and assigned Ser. No. 1088/KOL/2015, the entiredisclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a method and apparatus for systeminformation acquisition in wireless communication system.

BACKGROUND

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a ‘Beyond 4G Network’ or a‘Post LTE System’ or ‘Next generation of international mobiletelecommunication (IMT)-Advanced’.

The 5G communication system is considered to be implemented in higherfrequency (mmWave) bands, e.g., 10 GHz to 100 GHz bands, so as toaccomplish higher data rates. To mitigate propagation loss of the radiowaves and increase the transmission distance, the beamforming, massivemultiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO),array antenna, an analog beam forming, large scale antenna techniquesare discussed in 5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud radioaccess networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul, moving network based on mobile relay,cooperative communication, coordinated multi-points (CoMP),reception-end interference cancellation and the like.

In the 5G system, hybrid FSK and QAM modulation (FQAM) and slidingwindow superposition coding (SWSC) as an advanced coding modulation(ACM), and filter bank multi carrier (FBMC), non-orthogonal multipleaccess (NOMA), and sparse code multiple access (SCMA) as an advancedaccess technology have been developed.

In addition, a 5G wireless system is expected to address different usecases having quite different requirements in terms of data rate,latency, reliability, mobility etc. However, it is expected the designof the air-interface of 5G would be flexible enough to serve the UEshaving quite different capabilities depending on the use case and marketsegment the UE cater service to the end customer. Few example use casesthe 5G wireless system is expected to address is enhanced mobilebroadband (eMBB), massive machine type communication (m-MTC),ultra-reliable low latency communication (URLL) etc. The eMBBrequirements like tens of Gbps data rate, low latency, high mobility soon and so forth address the market segment representing the conventionalwireless broadband subscribers needing internet connectivity everywhere,all the time and on the go. The m-MTC requirements like very highconnection density, infrequent data transmission, very long batterylife, low mobility address so on and so forth address the market segmentrepresenting the internet of things (IoT)/internet of everything (IoE)envisioning connectivity of billions of devices. The URLL requirementslike very low latency, very high reliability and variable mobility so onand so forth address the market segment representing the industrialautomation application, vehicle-to-vehicle/vehicle-to-infrastructurecommunication foreseen as one of the enabler for autonomous cars.

The physical layer of wireless cellular system in both downlink (DL) anduplink (UL) operating in mmWave/cmWave would be based on newair-interface different from that of IMT-Advanced air-interface to meetthe challenging requirements and providing enhanced mobile broadbanduser experience. IMT-2020 wireless cellular system i.e. 5G system isexpected to deliver several 100 Mbps to a few tens of Gbps userexperienced data rates in comparison to wireless systems based oninternational mobile telecommunication (IMT)-Advanced. These very highdata rates need to be available ubiquitously across the coverage area.Apart from user experienced data rates 5G wireless cellular system isexpected to deliver on other requirements like peak data rate (few 10 ofGbps), reduced latency (down to 1 ms), better spectral efficiencycompared to IMT-Advanced system and many other requirements.

The 5G wireless cellular system is foreseen to be deployed in higherfrequency bands above 6 GHz (eg. 10 GHz˜100 GHz, also called mmWaveand/or cmWave) due to availability of large amount of spectrumbandwidths. In the initial phase of deployment 5G wireless cellularsystem is expected to be deployed in lower frequency bands below 6 GHzusing spectrum farming techniques. One of the requirements for 5G RAT isenergy efficiency; so the design of system information provisioningneeds to address the energy efficiency requirement to minimize always ONperiodic broadcast. Another aspect related to broadcasting of systeminformation is high signaling overhead in the context of 5G RAToperation in higher frequency bands (above 6 GHz) where DL beam sweepingoperation is inevitable to reach the coverage area of the cell.Broadcasting all the system information on the coverage beams which aresubject to DL beam sweeping may lead to excessive signaling overhead.

Therefore another design criterion for system information provisioningneeds to address the signaling overhead aspect. For the sake ofillustration of disclosed methods for acquisition of system informationby a user equipment (UE) it is assumed the air-interface of 5G wirelesscellular system would be based on orthogonal frequency divisionmultiple-access (OFDMA) radio access technology (RAT) in DL and UL.However the numerology (i.e. OFDM symbol duration, carrier spacing etc.)of 5G RAT is assumed to be different from the OFDMA numerology ofIMT-Advanced system.

SUMMARY

To address the above-discussed requirements of 5G communication systemsor IMT-2020 systems, it is a primary object to provide an apparatus anda method for system information acquisition in wireless communicationsystem.

In accordance with an aspect of the present disclosure, a method foracquiring system information by a user equipment (UE) in wirelesscommunication system, the method comprising acquiring at least onesystem configuration index (SCI) from a primary broadcast channel (PBCH)or a secondary broadcast channel (SBCH), determining a probe resourcebased on pre-configured parameters or parameters signaled in the PBCH orthe SBCH, transmitting a probe request on the determined probe resource,the probe request comprising the at least one SCI, receiving a proberesponse including at least the system configuration corresponding tothe at least one SCI included in the probe request, and applying andstoring the at least one system configuration acquired from the proberesponse.

In accordance with an aspect of the present disclosure, a method forproviding system information to a user equipment (UE) by an enhancednode B (eNB) in wireless communication system, the method comprisingdetermining a probe resource based on pre-configured parameters orparameters signaled in a primary broadcast channel (PBCH) or a secondarybroadcast channel (SBCH), receiving a probe request comprising at leastone system configuration index (SCI) on the determined probe resource,detecting a probe signal based on the probe request, determining whetherthere is a UE wanting a meaning of the at least one SCI in a cellcoverage area of the eNB, and transmitting a probe response including atleast one system configuration corresponding to the at least one SCI.

In accordance with an aspect of the present disclosure, a user equipmentfor acquiring system information in wireless communication system, theuser equipment comprising a processor module configured to acquire atleast one system configuration index (SCI) from a primary broadcastchannel (PBCH) or a secondary broadcast channel (SBCH), determine aprobe resource based on pre-configured parameters or parameters signaledin the PBCH or the SBCH, transmit a probe request on the determinedprobe resource, the probe request comprising the at least one SCI,receive a probe response including at least the system configurationcorresponding to the at least one SCI included in the probe request, andapply and store the at least one system configuration acquired from theprobe response.

In accordance with an aspect of the present disclosure, an enhanced nodeB (eNB) for providing system information to a user equipment (UE) inwireless communication system, the eNB comprising a processor moduleconfigured to determine a probe resource based on pre-configuredparameters or parameters signaled in a primary broadcast channel (PBCH)or a secondary broadcast channel (SBCH), receive a probe requestcomprising at least one system configuration index (SCI) on thedetermined probe resource, detect a probe signal based on the proberequest, determine whether there is the UE wanting a meaning of the atleast one SCI in a cell coverage area of the eNB, and transmit a proberesponse including at least one system configuration corresponding tothe at least one SCI.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 is an illustration of deployment of 5G wireless system depictingthe radio access network (RAN) architecture.

FIG. 2 is an illustration of one example of primary broadcast channel(PBCH) and secondary broadcast channel (SBCH) transmission and beamreference signal from a cell of 5G wireless system according to oneembodiment of the present disclosure.

FIGS. 3A and 3B are an illustration of one example of a probe resourceprovided to a UE for transmitting probe request on a cell of 5G wirelesssystem according to one embodiment of the present disclosure.

FIG. 4 is an illustration of generalized probe request and proberesponse procedure to acquire system information initiated by a UE whenpowered on and remaining in an idle mode according to one embodiment ofthe present disclosure.

FIG. 5 is an illustration of generalized probe request and proberesponse procedure to acquire system information initiated by a UE whenpowered on and transitions to connected mode according to one embodimentof the present disclosure.

FIG. 6 is an illustration of generalized probe request and proberesponse procedure to acquire system information initiated by a UE whenpowered on and transitions to connected mode according to anotherembodiment of the present disclosure.

FIG. 7 is an illustration of two step probing procedure based on probepreamble transmission to acquire system information initiated by a UEwhen powered on according to one embodiment of the present disclosure.

FIG. 8 is an illustration of two step probing procedure based on probeON/OFF signal transmission to acquire system information initiated by aUE when powered on according to another embodiment of the presentdisclosure.

FIG. 9 is an illustration of four step probing procedure based on probepreamble transmission to acquire system information initiated by a UEwhen powered on according to one embodiment of the present disclosure.

FIG. 10 is an illustration of four step probing procedure based on probeON/OFF signal transmission to acquire system information initiated by aUE when powered on according to another embodiment of the presentdisclosure.

FIGS. 11A and 11B are an illustration of scenarios concerning handlingof change in system configuration index (SCI) according to oneembodiment of the present disclosure.

FIGS. 12A and 12B are an illustration of operations at the UE side toacquire system information based on two step probing procedure accordingto one embodiment of the present disclosure.

FIG. 13 is an illustration of operations at the UE side to acquiresystem information based on four step probing procedure according to oneembodiment of the present disclosure.

FIG. 14 is an illustration of operations at the eNB side to provisionsystem information based on probing procedure according to oneembodiment of the present disclosure.

FIG. 15A is a block diagram of 5G eNB depicting the hardware andsoftware modules for realizing the methods proposed in the presentdisclosure.

FIG. 15B is a block diagram of UE depicting the hardware and softwaremodules for realizing the methods proposed in the present disclosure.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.Definitions of certain words and phrases are provided throughout thispatent document, those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases. For example the5G communication systems or of IMT-Advanced systems is simply referredas wireless system or RAT throughout this patent document. Anotherexample the terminal is referred as User Equipment (UE) throughout thispatent.

DETAILED DESCRIPTION

FIGS. 1 through 15B, discussed below, and the various embodiments of thepresent disclosure used to describe the principles of the presentdisclosure in this patent document are by way of illustration only andshould not be construed in any way to limit the scope of the disclosure.Those skilled in the art will understand that the principles of thepresent disclosure may be implemented in any suitably arrangedcommunication technologies. Hereinafter, operation principles ofexemplary embodiments of the present disclosure will be described indetail with reference to accompanying drawings. In the followingdescription of the present disclosure, a detailed description of knownconfigurations or functions incorporated herein will be omitted when itis determined that the detailed description may make the subject matterof the present disclosure unclear. Terms described later are defined inconsideration of the functions of the present disclosure, but may varyaccording to the intention or convention of a user or operator.Therefore, the definitions should be made based on contents throughoutthe specifications.

In the present disclosure, the mmWave/cmWave band is considered commonscenario for deployment of 5G RAT and hence the procedures are describedtaking the radio characteristics in those bands. However, in practicaldeployments it is possible to apply the air-interface of 5G wirelesscellular system even below 10 GHz band, therefore the applicability ofthe 5G RAT and the procedure disclosed in the present disclosure shouldnot be considered strictly limited to mmWave/cmWave bands. Since theradio characteristics is different for frequencies in the mmWave/cmWavebands compared to frequencies in sub 6 GHz bands, it is also expected 5Gwireless cellular system would have native support for beamformingtechniques for both broadcast and unicast transmissions towards UE toovercome short propagation distances of radio signals at mmWave/cmWavefrequencies.

In the present disclosure, 5G wireless system is explained as anexample. It is readily understood to those skilled in the art that thevarious embodiments of the present disclosure are applicable to othercommunication systems through some modifications without departing fromthe scope of the present disclosure.

FIG. 1 is an illustration of deployment of wireless system depicting theradio access network (RAN) architecture.

Referring to FIG. 1, the RAN level network architecture consisting ofplurality of 5G enhanced node Bs (eNBs) (103 a, 103 b so on and soforth, or base stations) serving plurality of cell(s) of the 5G wirelessair-interface (104 a, 104 b so on and so forth) in standalone mode isshown. A Gateway (101) can be connected to 1 . . . r 5G nodes of 5G RATi.e. 5G eNBs (103) for handling the frequency carrier(s) in the cellcoverage area. One 5G eNB (103) may be connected to more than one GW(101). Within the coverage of 5G eNB1 and 5G eNB2 (103 a and 103 b)plurality of UE's (102 a, 102 b, 102 c, 102 x so on and so forth) whichsupport multiple RAT functionalities like (GSM, UMTS, LTE) and also 5GRAT functionalities (5G) are served by one or more cell(s) (i.e 104 a,104 b, etc). Regardless of the UE support type each UE can access atleast one carrier based on 5G RAT.

The 5G wireless cellular system hierarchy would consist of 1 . . . k eNB(103) nodes such that one eNB (103) node consist of 1 . . . m Cell(s).Further, one Cell consists of 1 . . . n transmission points(Transmission Points (TPs) i.e 105 a, 105 b, 105 c so on and so forth)such that the fronthaul between eNB (103) node and TPs (105 a, 105 b,105 c etc) is ideal. The TPs (105 a, 105 b, 105 c etc) of one cell ofeNB (103) will operate to provide 1 . . . p “DL coverage beams”.Further, it seems reasonable to assume all TPs belonging to the samecell are “time synchronized” i.e. same radio frame and System FrameNumber (SFN) timing. The radio frame duration of IMT-Advanced is 10 msand the SFN range is 0-1023. The numerology of 5G RAT is assumed suchthat the IMT-Advanced radio frame is either multiple of radio frame of5G RAT or radio frame of 5G RAT is exactly 10 ms. Therefore, the SFNrange of 5G RAT is either 0-1023 or multiple of IMT-Advanced SFN range.This is needed to support non-standalone deployment of 5G wirelesssystem. It is expected that the initial deployment of 5G wireless systemoperating in mmWave/cmWave bands would operate as non-standalone systemto provide additional radio resources to the UE which would be connectedto IMT-Advanced or previous generation system for coverage purpose. Withthe assumption that 5G wireless system would be added as a capacitylayer to existing IMT-Advanced deployments then from the initialstandardization phase perspective the RAN architecture would be based oncarrier aggregation (CA) or dual-connectivity (DC) framework specifiedby 3rd generation partnership project (3GPP). In an embodiment of thepresent disclosure, the radio frame duration of IMT-Advanced system issame as radio frame duration of 5G RAT or the radio frame duration ofIMT-Advanced system is integer multiple of radio frame duration of 5GRAT. The maximum number of DL coverage beams ‘p’ will typically dependon frequency used; i.e. can be larger in higher frequency bands due tosmaller antenna separation at the TPs of eNB (103). The cell of the 5Gwireless system is identified by a “Cell Identifier (cell id)”. The UEcan obtain the cell id from the synchronization signal (SS) transmittedby the Cell of the 5G RAT.

It is assumed the UE (102) which supports legacy RAT, IMT-Advanced RATand 5G RAT is not aware of TPs (105 a, 105 b, 105 c etc) of the 5Gwireless system. The TPs operate together to provide beams to the UE andnotion of TP is transparent to the UE. Therefore, there is no “TPIdentifier (TP-Id)” provided to the UE over the radio of 5G RAT. The UE(102) is aware of cell of eNB (103) and beams covering the cell i.e. theUE shall detect the Synchronization Signal to determine a “CellIdentifier” (cell id) and decode the Beam Index Sequence to determine a“Beam Identifier (beam-id)”. Further, two types of DL beams areconsidered: 1) coverage beams and 2) dedicated beams. The coverage beamsprovide the coverage for cell (104) of 5G system with a fixed set ofdirected coverage beams, also called as “grid of beams”. Coverage beamscover a relatively wide area, i.e. they are not very “sharp or directed”and can thus only support relatively low data rates. For example, in acell (104) there could be less than 10 coverage beams or more than 10 DLcoverage beams. As an example, each coverage beam could cover 30-60degree sector angle such that gird of coverage beams cover 100-200 mradius circular area. Each coverage beam is identified by a “beam id”.The coverage beams transmit the synchronization signal (SS) andreference signals for beam signal strength measurements. These referencesignals are generically referred as beam reference signal (BRS) and usedfor radio resource management (RRM) measurements. Coverage beams areused for transmitting DL common channel signaling e.g. RACH response.Coverage beams carry control channel transmissions like enhancedphysical downlink control channel (ePDCCH) and user data physicaldownlink shared channel (PDSCH) can also be transmitted on coveragebeams when dedicated beams to the UE have been lost. For demodulationpurpose when ePDCCH/PDSCH is transmitted on coverage beam thenDemodulation Reference Signal (DMRS) is also transmitted. Dedicatedtransmissions towards UE (ePDCCH/PDSCH) may potentially use even moredirected and sharp beams (e.g. UE specific pre-coding) on so called“Dedicated Beams”. Coverage area of dedicated beams would be muchsmaller in terms of beam width compared to coverage beams (e.g. ½, ¼ or⅛th of coverage beam area).

Dedicated beams are managed based on UE measurement on channel-stateinformation-reference signal (CSI-RS) and UE provides CSI feedback atPHY layer. To demodulate ePDCCH/PDSCH carried on dedicated beams, DMRSis also transmitted on dedicated beam. Since UE just see DMRS kind ofreference signals coming from the cell of the system the notion ofcoverage beam and dedicated beam is transparent to the UE for PDSCHreception point of view. However, notion of coverage beam is known to UEfor reception of synchronization signal. Therefore, when eNB (103)detects UE has lost dedicated beams based on CSI-RS measurement feedbackand UE is scheduled data on coverage beam then UE will not be aware thatwhether the transmission is coming from a coverage beam. To the UE thislooks like any other transmission coming from a dedicated beam. Celledge bitrates on coverage beams will be much lower than cell edgebitrates achievable by dedicated beams. UE transmission in the UL mayalso be carried on UL beams. However, the number of UL beams is expectedto be less compared to the number of DL beams considering the UE sizeand number of antenna's at the UE.

In the non-standalone mode the Cell parameters of the 5G RAT (i.e systeminformation) which are cell specific like DL/UL bandwidth, TDDconfiguration, PRACH configuration, PDSCH configuration, physical uplinkcontrol channel (PUCCH) configuration, PUSCH configuration, SoundingReference Signal (SRS) configuration, UL power control configuration,MAC configuration, RLC configuration, PDCP configuration etc. isprovided to the UE through dedicated signaling from the Primary Cell(PCell) served by the LTE node. The system information contains theLayer1/Layer2 (L1/L2) configuration which in general is called the SCGconfiguration information when provided to the UE in non-standalonemode. The system information containing the L1/L2 configuration ingeneral is called the radio resource configuration information whenprovided to the UE in standalone mode. The SCG configuration informationis provided to the UE (102) in a radio resource control (RRC) containerthrough the Master eNB (i.e LTE node) via dedicated RRC signaling fromthe PCell. In addition the DL beam mobility measurement configurationwhich includes the CSI-RS configuration including the CSI-RS processesthat points to the CSI-RS resource configuration including the non-zeroPower (NZP), zero power (ZP) and interference measurement resource (IMR)resources and the reporting configuration is provided to the UE throughdedicated signaling from the PCell served by the LTE node. In astandalone mode, the DL beam mobility measurement configuration isprovided to the UE directly by the node. Based on the CSI-RSconfiguration the UE in connected mode should monitor the NZP and IMRresources to perform CSI measurements that includes at least channelquality indicator (CQI), rank indicator (RI), precoding matrix index(PMI), CSI-RS RSRP measurements on the resources configured for the UE.There is no need to provide the UE with intra-frequency configuration,inter-frequency configuration and inter-RAT configuration in thenon-standalone mode since the idle mode mobility is supported on the LTEcarrier and not on the 5G RAT carrier. However these configurationswould be needed in the standalone mode. The terms PRACH, physicaldownlink shared channel (PDSCH), physical uplink control channel(PUCCH), physical uplink shared channel (PUSCH), SRS for the physicalchannels of 5G RAT are used for simplicity so that someone with ordinaryskills of the IMT-Advanced system can correlate with terms used inIMT-Advanced system.

In the standalone mode of operation of 5G wireless system the cellspecific parameters (L1/L2) configuration i.e radio resourceconfiguration and other configurations for idle mode mobility need to beprovided the UE. Traditionally in legacy wireless system such parametersare periodically broadcasted in the cell coverage area in the form ofone or more system information blocks (SIBs) in addition to the masterinformation block (MIB). On acquiring the MIB and SIBs related to cellaccess and idle mode mobility the UE can camp on a cell and then startinitial access on the camped cell. Table 1 shows the MIB/SIB broadcastedin LTE and the purpose each SIB serve. One of the requirements for 5GRAT is energy efficiency; so the design of system informationprovisioning needs to address the energy efficiency requirement tominimize always ON periodic broadcast. Another aspect related tobroadcasting of system information is high signaling overhead in thecontext of 5G RAT operation in higher frequency bands (above 10 GHz)where DL beam sweeping operation is inevitable to reach the coveragearea of the cell. Broadcasting all the SIBs on the coverage beams whichare subject to DL beam sweeping may lead to excessive signalingoverhead. Therefore, another design criterion for system informationprovisioning needs to address the signaling overhead aspect.

TABLE 1 MIB/SIB Main purpose MIB Cell access SIB1 Cell access SIB2 RadioResource Configuration SIB3 Cell reselection SIB4 Cell reselectionintra-frequency SIB5 Cell reselection inter-frequency SIB6 Inter-RATreselection UMTS SIB7 Inter-RAT reselection GERAN SIB8 Inter-RATreselection CMDA2000 SIB9 Home eNB name SIB10 ETWS SIB11 ETWS SIB12 CMASSIB13 MBSFN SIB14 EAB SIB15 MBMS SAI list SIB16 GPS/UTC time SIB17 WLANSIB18 D2D Communication SIB19 D2D discovery

FIG. 2 is an illustration of one example of primary broadcast channel(PBCH) and secondary broadcast channel (SBCH) transmission and beamreference signal from a cell of wireless system according to oneembodiment of the present disclosure.

Referring to FIG. 2, one example of primary broadcast channel (PBCH) andsecondary broadcast channel (SBCH) transmission and beam referencesignal (200) from a cell of 5G wireless system is shown. For standalonemode of operation a default PBCH cycle and SBCH cycle which is frequencyagnostic can be specified in 3GPP specifications. As an example thedefault PBCH cycle (210 a, 210 b, 210 c so on and so forth) can bespecified as 20 or 40 ms. Similarly a default SBCH cycle (215 a, 215 b,215 c so on and so forth) can be specified as 40 or 80 ms. The PBCH andSBCH transmission are subject to DL beam sweeping over plurality of DLcoverage beams in order to reach UEs in entire cell coverage area. Theoffset (225 a, 225 b so on and so forth) between the PBCH and SBCH caneither be default offset or indicated in the PBCH. The PBCH is blindlydetected by the UE during each synchronization signal period (250). TheDL beam sweeping period (220 a, 220 b, 220 c so on and so forth)comprising the PBCH aligns with the start of the radio frame of the cellsince the PBCH period includes the physical synchronization signals.During the DL beam sweeping period (220 a, 220 b, 220 c, etc.) pluralityof DL coverage beams (240 a, 240 b, 240 c, . . . 240 y, 240 z) aretransmitted consecutively in time in different directions to providecoverage to UEs in the area covered by sweeping the beams. The PBCH istransmitted during the synchronization signal period (250) which may ormay not cover all the OFDM symbols within the Transmission Time Interval(TTI) of 5G RAT depending on the exact physical layer design.

The synchronization signal period (250) consists of a plurality of OFDMsymbols of 5G RAT and cover the minimum bandwidth consisting ofplurality of subcarriers of 5G RAT required for the transmission of atleast the synchronization signal (251), beam index sequence (252),master information block (MIB) (253) and beam reference signals (BRS)(254). The synchronization signal (251) consists at least the primarysynchronization signal (i.e PSS), the secondary synchronization signal(i.e SSS) and the beam index sequence (252). The PSS/SSS (251), beamindex sequence (252) and MIB (253) are transmitted on a plurality ofOFDM symbols and plurality of subcarriers during the PBCH period orsynchronization signal period (250) subject to beam forming logicassociated with DL beam index #1 (240 a). The beam index sequence (252)indicates the DL beam index #1. In the next synchronization period (250)the PSS/SSS (251), beam index sequence (252) indicating the DL beamindex #2 and MIB (253) are transmitted on plurality of OFDM symbols andplurality of subcarriers subject to beam forming logic associated withDL beam index #2 (240 b). This is referred as DL beam sweeping on PBCHwherein the PSS/SSS (251), beam index sequence (252) indicating the DLbeam index #M and MIB (253) are transmitted on plurality of OFDM symbolsand plurality of subcarriers in the mth PBCH period or synchronizationperiod (250) subject to beam forming logic associated with DL beam index#M (240 z). On blindly decoding the PSS/SSS (251) and beam indexsequence (252), the UE determines the Physical Cell Identity (PCI) orcell id and the timing compensation to be applied to determine the radioframe boundary of the cell transmitting the synchronization signal. Thebeam reference signals i.e BRS (254) are reference signals transmittedon plurality of OFDM symbols and plurality of subcarriers excluding theresources occupied by PSS/SSS (251) beam index sequence (252) and MIB(253). The resources used for transmitting the BRS (254) on DL beamindex #m depend on the PCI of the cell and the DL beam index. The BRS(254) is transmitted during the synchronization period (250) subject tothe corresponding beam forming logic associated with DL beam index #m.In FIG. 2 the first beam during the DL beam sweeping period is depictedDL beam index #1 and subsequent beams in time as DL beam index #2 so onand so forth. Such a depiction should not be considered as a limitingcase because the starting beam can be any beam uniquely identified bythe beam index sequence subject to maintaining the beam sequence and thenumber of beams same during the DL beam sweeping period. For eg. thestarting beam can be DL beam index #11 followed by DL beam index #12while keeping the number of beams during the DL beam sweeping periodequal to M.

After decoding the PSS/SSS (251) and beam index sequence (252); UE cometo know the PCI and the DL beam index; hence the resources where it canperform measurements at physical layer on BRS. These measurementsindicate the estimate of signal strength of beam index #m and reportedto higher layer for cell mobility evaluations. Generically thesemeasurements are termed as BRS Reference Signal Received Power(BRS_RSRP) and BRS Reference Signal Received Quality (BRS_RSRQ)providing an estimate of signal strength on received beam from the celldetected by the UE. For standalone mode of operation where the UE needsto camp on the cell of 5G RAT, the measurements on BRS i.eBRS_RSRP/BRS_RSRQ are used for idle mode mobility during cell selectionand/or cell re-selection. Before camping on the cell of 5G RAT, UEblindly decodes the MIB (253) which contains at least: the DL systembandwidth. System Frame Number (SFN), Probing configuration, ePDCCHconfiguration, SBCH offset. In an embodiment of the present disclosure,the probing configuration and ePDCCH configuration is broadcasted inPBCH wherein the probing configuration comprises at least: one or moreroot sequences, DMRS reference power, probe offset, probe preamblegroup, and one or more probing resource configuration.

On blindly decoding the PBCH the UE determines the radio frame boundary,PCI, SFN, DL system bandwidth, best DL beam index, BRS resources formeasurements, SBCH offset and probing configuration. Since the SFN andbest DL beam index is determined and the SBCH cycle (215) and SBCHOffset (225) is known the UE can decode the SBCH on the determined bestDL beam index to acquire further parameters concerning camping and cellaccess. The SBCH is decoded by the UE during the SBCH period (260). TheDL beam sweeping period (230 a, 230 b so on and so forth) comprising theSBCH contains the parameters for cell camping and cell access andoptionally BRS. During the DL beam sweeping period (230 a, 230 b etc.)plurality of DL coverage beams (245 a, 245 b, 245 c, . . . 245 y, 245 z)are transmitted consecutively in time in different directions to providecoverage to UEs in the area covered by sweeping the beams. The SBCH istransmitted during the SBCH period (260) which may or may not cover allthe OFDM symbols within the transmission time interval (TTI) of 5G RAT.The SBCH may be addressed on the ePDCCH by the SI-RNTI. The SBCH period(260) consist of plurality of OFDM symbols and plurality of subcarriersof 5G such that the SBCH burst (261) may occur in the minimum bandwidthor some other frequency resources of the entire DL system bandwidth. TheSBCH period consists of at least the system information block (SIB)(261) and optionally the beam reference signals (BRS) (262). The SIB(261) contains at least: the primary PLMN, a plurality of systemconfiguration index (SCI), tracking area code (TAC), parameters foraccess control barring (ACB).

The requirement to limit broadcast information size in 5G wirelesssystem employing beamforming can be made possible if a large majority ofparameters is not directly visible on broadcast but only “hidden” undera System Configuration Index or system configuration identifier (SCI).In an embodiment of the present disclosure, the system configurationindex (SCI) is an index/identifier which is associated with a set ofsystem information parameters and corresponding parameter values whichare provided by the network on UE sending the probe or request. Instandalone mode of operation of the 5G wireless system the MIB and SCIis required to provide at least system information to enable the UE toperform initial random access on the camped cell and send a connectionrequest and receive connection response. Furthermore, upon knowing themeaning of SCI it should provide sufficient information so that IDLEmode UEs knows whether they are applying the correct mobilityconfiguration. In the present disclosure the system informationprovisioned on UE demand or UE request is referred as “Other systeminformation”. Network may provide the “Other system information” to UEvia dedicated signaling or through broadcast. For certain systeminformation, it might be more efficient to provide the information bybroadcast (e.g. ETWS, CMAS) since many UEs have to obtain theinformation. Based on these assumptions, referring to the LTE MIB/SIBslisted in Table 1 it can be determined whether the concerning systeminformation parameter in the MIB/SIB is relevant to behidden/referred/covered by the SCI. First it need to be examined fromall broadcast parameters in the LTE MIB/SIB whether the parameter wouldbe relevant for 5G (next generation wireless system), and if it isdetermined it is relevant then to determine whether the parameter can beprovided either in the MIB on the PBCH or can be hidden/referred/coveredby the SCI. On further analysis of Table 1, it seems good to excludeSIBs 9, 10, 11, 12 to be hidden/covered/referred by SCI since thisinformation can be provided to UE with dedicated signaling after initialrandom access in 5G RAT. It may also seem reasonable to exclude SIBs 13,15 since MBMS might not be provided by 5G RAT in the first phase. So,SIBs 13, 15 can be provided to UE with dedicated signaling if MBMS isintended to be provided by 5G RAT. Therefore it seems reasonable tofocus the analysis on essential SIBs: i.e access related MIB/SIBs (MIB,SIBs 1, 2, 14 and mobility related SIBs 3, 4, 5, 6, 7, 8 to determinewhich parameter is relevant for 5G RAT and then determine whether it canbe broadcasted separately because the parameter changes dynamically orit can be hidden/covered/referred by SCI. A number of broadcastparameters seem not so suitable to be hidden/referred/covered by SCI.This is especially true for parameters where the values of theseparameters will potentially change dynamically. This concerns e.g. SFN,TAC, Cell identifier, DL coverage Beam index, access control parametersetc. These parameters are therefore not covered by SCI but broadcastedseparately in PBCH/SBCH in addition to a plurality of SCI. Further, thePLMN identity would be needed by the UE to decide whether to camp on acell if it meets the cell selection criterion and then start the probingprocedure on the camped cell to request the other system information.However, if the PLMN identity is covered by the SCI then the UE does notwhether the cell meeting the cell selection criterion belongs to theUE's primary PLMN. Therefore the primary PLMN should not be covered bySCI but broadcasted separately in PBCH/SBCH in addition to SCI. Anotherreason to probably keep these parameters outside the SCI space is thatinclusion would potentially “explode” the SCI space. Large number ofparameters could potentially be handled by a plurality of SCI. Assumingthat the range of actual used values of the parameters is lower than therange of values defined in the standard, this could significantly reducethe broadcast message size. Further referring to Table 1, apart from thewhitelist and blacklist that exist in SIB3, SIB4 and SIB5 none of theparameters therein seem location specific, so can behidden/covered/referred by the SCI. In SIB6 and SIB7 there is nowhitelist signaled so as a result none of the information in SIB6 seemslocation specific, so can be hidden/covered/referred by the SCI. In SIB8the neighbor cell lists may have same problem as whitelist in SIB4 andthe barring parameters in SIB8 might require special handling due tofrequent update and hence can be excluded to be hidden/covered/referredby SCI. Table 2 is high level summary of which system informationparameters can be hidden/covered/referred by SCI.

TABLE 2 Covered by a plurality of MIB/SIB Main purpose SCIs Remarks MIBCell access No Dynamic parameters of MIB are broadcasted periodicallySIB1 Cell access allowed Yes (at least SCI needs to provide relevantCell partly) Access information SIB2 Radio Resource Config Yes (at leastSCI needs to provide relevant radio partly) resources configuration forcell access. SIB3 Cell reselection Yes (at least IDLE mode UE needs toknow what partly) radio resource configuration to use SIB4 Cellreselection Yes (at least Depending on support e.g. cell/TP intra-freqpartly) specific offsets in 5G. Cell specific offsets (or beam specificoffsets) would concern very localised infor- mation and probably not soeasy to cover by SCI SIB5 Cell reselection Yes (at least IDLE mode UEneeds to know whether inter-freq partly) in the 5G area it is, anystored inter-freq reselection information is still valid. SIB6 Inter-RATreselection May be Yes (at IDLE mode UE needs to know whether UMTS leastpartly) in the 5G area it is, any stored inter-RAT reselectioninformation is still valid. Depends on 5G ← → 3G mobility need to besupported SIB7 Inter-RAT reselection May be Yes (at IDLE mode UE needsto know whether GERAN least partly) in the 5G area it is, any storedGERAN reselection information is still valid. Depends on 5G ←→ 2Gmobility need to be supported SIB8 Inter-RAT reselection May be Yes (atIDLE mode UE needs to know whether CMDA2000 least partly) in the 5G areait is, any stored CDMA2000 reselection information is still valid.Depends on 5G ←→ CDMA mobility need to be supported SIB9 Home eNB nameNo Can be provided with dedicated SIB10/SIB11/ ETWS/CMAS Nosignalling/or introduce broadcast SIB12 signalling in stand-alone systemSIB13/SIB15 MBSFN/MBMS SAI list No No MBSFN on 5G cells SIB14 EAB YesRelevant to know whether RACK is allowed SIB16 GPS/UTC time No Notessential even in LTE SIB17 WLAN No No if it can be assumed that theseparameters can always be provided with dedicated signalling. SIB18 D2DCommunication Yes Will need to be covered if D2D SIB19 D2D discovery Yescommunication in IDLE mode is to be supported, and the UE needs to knowwhat parameters to use in this location.

On decoding the PBCH/SBCH the UE determines the primary PLMN, TAC, ACBparameters and SCI value; however, the UE does not know what the SCIvalue refers to. On decoding the PSS/SSS, beam index sequence andacquiring the contents of the MIB and SIB, the UE can performBRS_RSRP/BRS_RSRQ measurements and can camp on a cell of the 5G RATbased on some cell selection criterion. On simple example of cellselection criterion is determining whether the detected cell belongs toprimary PLMN of the UE and then comparing the BRS_RSRP/BRS_RSRQmeasurement derived from one or more coverage beam measurements with athreshold either pre-defined in specification or indicated in SIB tocheck if the measurement is above the threshold to decide camping on thedetected cell. In an embodiment of the present disclosure, a pluralityof system configuration index may be broadcasted in SBCH; wherein thesystem configuration index (SCI) is a value which refers to set ofparameters concerning system configuration and the correspondingparameter values which are provided by the network on UE sending theprobe or request. In another embodiment of the present disclosure, aplurality of system configuration index may be broadcasted in PBCH;wherein the system configuration index (SCI) is a value which refers toset of parameters concerning system configuration and the correspondingparameter values which are provided by the network on UE sending theprobe or request. The SCI value refers not only to the set of systemconfiguration parameters but also to the values of those parameters. Inan embodiment of the present disclosure, the UE is required to performthe probing procedure in order to find out the meaning of SCI value orwhat the SCI value refers to. In an embodiment of the presentdisclosure, the idle mode mobility of UE supporting 5G RAT is based onBRS measurements which represent the cell quality metric derived fromone or more coverage beam measurements. FIG. 2 is just an example ofPBCH and SBCH transmission and should not be considered as limitingcase. It may be possible that the PBCH period comprises PSS/SSS, beamindex sequence and a burst comprising the contents of MIB and SIB. Inanother alternative it is possible the PBCH period comprises the PSS/SSSand beam index sequence while the SBCH period comprises the contents ofMIB and SIB.

In the non-standalone mode of operation of the 5G system thesynchronization signal cycle, the length of DL beam sweeping period, thesynchronization signal period, the bandwidth of the synchronizationsignal and the number of DL fixed beams transmitted during the DL beamsweeping period is provided to the UE from the PCell served by the LTEMeNB. In the standalone mode of operation of the 5G system thesynchronization signal cycle, the length of DL beam sweeping period, thesynchronization signal period, the bandwidth of the synchronizationsignal and the number of DL fixed beams transmitted during the DL beamsweeping period is pre-defined in the standard specification.

FIGS. 3A and 3B are an illustration of one example of a probe resourceprovided to a UE for transmitting probe request on a cell of wirelesssystem according to one embodiment of the present disclosure.

FIG. 3A is an illustration of one example of probe resources provided toa UE (300 a) for transmitting a probe request on a cell of wirelesssystem where every instance of the probing opportunity is associatedwith PBCH period. The PBCH is transmitted periodically with a PBCH cycle(315) eg. 20 or 40 ms and the PBCH transmission is subject to DL beamsweeping over a plurality of DL coverage beams during the PBCH period(310). The probe offset (325 a, 325 b so on and so forth) between thePBCH period (310) and probe resource (320) can either be default offsetor indicated in the probing configuration signaled in the PBCH. Aftercamping on the cell of 5G RAT in order to know the meaning of systemconfiguration index (SCI) acquired from SBCH/PBCH; the UE applies theprobe offset (325) with respect to start of DL beam sweeping period(310) to initiate probing procedure based on the probing configurationsignaled in the PBCH. Some parameters concerning the probing procedurewhich are static can be pre-defined or pre-configured in the standardspecification and there is no need to provide such parameters in theprobing configuration signaled to the UE in the PBCH. Examples of suchparameters are the probe offset, probe power ramping step, probing timeslot, probe bandwidth, probe response window size, maximum number ofprobe transmission attempts etc. The probe request can be either basedon preamble transmission or based on simple ON/OFF physical layer signaltransmission. The probe request transmitted on the probe resource (320)can be subject to either UL beam sweeping or repetition. In a TDD based5G wireless system after UE determines the best DL beam index, based onchannel reciprocity the UE may transmit the probe signal in the ULdirection based on the best DL direction. In order the probe signal isreceived by the eNB, the UE may repeat the probe signal several times onthe probe resource (320). Alternatively, the UE may apply UL beamsweeping on the probe signal while transmitting on the probe resource(320). During the UL beam sweeping period (320 a, 320 b, 320 c, etc.)the probe signal is transmitted with same power on plurality of UL beams(330 a, 330 b, 330 c, . . . 330 y, 330 z) consecutively in time indifferent UL direction towards the 5G eNB or the probe signal is simplyrepeatedly transmitted with same power during the probe repetitionperiod (320 a, 320 b, 320 c, etc) on each probe request opportunity(340). The length of the probing time slot (350) and the probe bandwidth(550) are static parameters and can be pre-defined or pre-configured inthe standard specification. Alternatively, these parameters can besignaled in the probing configuration in the PBCH/SBCH. The startingresource block of the probe time slot is determined based on thefrequency offset (360) with reference to lowest index resource block. Inan embodiment of the present disclosure, the pre-configured orpre-defined parameters for probing includes at least the probe offset,probe power ramping step, probing time slot, probe bandwidth, frequencyoffset with respect to lowest indexed resource block of UL bandwidth,probe repetition period, probe response window size, maximum number ofprobe transmission attempts.

FIG. 3B is an illustration of another example of probe resourcesprovided to UE (300 b) either in time domain and/or frequency domain fortransmitting a probe request on a cell of wireless system where eachinstance of the probing opportunity is associated with UE capability andDL beam index. The PBCH is transmitted periodically with a PBCH cycle(315) eg. 20 or 40 ms and the PBCH transmission is subject to DL beamsweeping over plurality of DL coverage beams during the PBCH period(310). The probe offset (325 a, 325 b so on and so forth) between thePBCH period (310) and probe resource (320) can either be default offsetor indicated in the probing configuration signaled in the PBCH. When theprobe request is based on simple ON/OFF physical layer signal then theprobe request is transmitted on plurality of probe resources associatedwith the UE capability. Such probe resources are distributed either intime domain and/or frequency domain. The time domain probe resource (320a) may be associated with eMBB capable UE while the probe resource (320aa) may be associated with m-MTC capable UE so on and so forth. Thesetime domain distributed probe resources (320 a) and (320 aa) aredifferentiated in time domain with the parameter probe slot period(326). Similarly, the frequency domain probe resource (320 a) may beassociated with DL beam index #1 while the probe resource (320 aa) maybe associated with DL beam index #2 so on and so forth. The frequencydomain distributed probe resources (320 a) and (320 aa) aredifferentiated in frequency domain with the parameter probe slot offset(327). Therefore, each probe resource in time and frequency isassociated with UE capability and DL beam index. Such a matrix ofmapping probe resources to UE capability and DL beam index is shown inTable 6. The parameters probe offset, probe slot period, probe slotoffset, probe resource id matrix can be provided in the probingconfiguration signaled to the UE in the PBCH. In an embodiment of thepresent disclosure, the probing configuration includes at least theprobe offset, the length of probe time slot, the probe bandwidth, theprobe frequency Offset with respect to lowest indexed resource block ofUL bandwidth, the probe repetition period or UL beam sweeping period,the number of UL fixed beam, the periodicity of probe opportunity, powerramping step-size, timers used during probing procedure. In anotherembodiment of the present disclosure, UE may be provided with otherinformation like mapping between the set of probe preambles and the UEbasic capability, mapping between a subset of probe preambles and DLcoverage beams, probe slot period and probe slot offset if a pluralityof probe opportunities are configured in time and/or frequency domainrespectively. An example of a plurality of probe opportunitiesassociated with UE capability configured in time and/or frequency domainis depicted in FIG. 3B.

FIG. 4 is an illustration of generalized probe request and proberesponse procedure to acquire system information initiated by a UE whenpowered on and remaining in an idle mode according to one embodiment ofthe present disclosure.

Referring to FIG. 4, at step 401 the UE supporting 5G RAT is powered ONand the UE starts searching for a synchronization signal on thefrequency supported by the UE RF capability. The UE periodicallysearches the minimum bandwidth on the concerned carrier frequency todecode the synchronization signal and subsequently acquire the MIB fromthe PBCH. On blindly decoding the PSS/SSS, beam index sequence andacquiring the contents of the MIB i.e. PBCH and subsequently SIB i.e.SBCH, the UE performs BRS_RSRP/BRS_RSRQ measurements on one or morecoverage beams. The UE decides to camp on a cell of the 5G RAT based onsome cell selection criterion and the PLMN selection rule. The UEacquires a plurality of SCI value(s) from the PBCH/SBCH but does notknow the meaning of the SCI value(s).

At step 402 the UE determines the probe resources based on thepre-configured parameters or parameters signaled in PBCH/SBCH.

At step 403, on the determined probe resource on the UL carrierfrequency the UE initiates the transmission of the probe requestaccording to probing configuration received in PBCH. The probe signal istransmitted by the UE with transmission power set according to theestimate of the DL pathloss calculated from the received powermeasurement eg. BRS_RSRP on best DL beam determined. The probe signal istransmitted with same power on a plurality of UL beams consecutively intime in different UL direction towards the eNB during the UL beamsweeping period or the probe signal is simply repeatedly transmittedwith same power during the probe repetition period on each probe timeslot. The UE starts the probe response window timer expecting theresponse from the eNB.

At step 404, one or more TPs (i.e. reception points) belonging to one ormore eNBs detect a probe signal on the probe resource. On detecting theprobe signal one or more TPs belonging to one or more eNBs determinethat there is a UE in its cell coverage area who has acquired SCI wantsto the know the meaning of SCI.

At step 405, one or more TPs belonging to one or more eNBs transmit theprobe response which includes the system information (i.e. L1/L2configuration or system information blocks) corresponding to a pluralityof SCI values which the responding nodes are transmitting in the PBCHor/and SBCH. The probe response message can be addressed byprobing-radio network temporary Identifier (Pr-RNTI) in the beamspecific search space to UE on the DL coverage beam identified by the DLbeam index. If the responding node does not know the best DL beam indexfor the UE requesting probe response, then the probe response messagemay be subject to DL beam sweeping. Alternatively, if the respondingnode knows the best DL beam index for the UE requesting probe response,then the probe response message can be addressed by the probing radionetwork temporary identifier (Pr-RNTI) in the beam specific search spaceto the UE only on the DL coverage beam identified as best DL beam index.It is also possible to repeat the probe response message on the DLcoverage beam identified as best DL beam index for the requesting UE.Upon expiry of the probe response window if the UE who transmitted probesignal at step 403 did not receive the probe response then the UE canre-transmit the probe request with increased power compared to theprevious probe signal transmission power wherein, the power increase isdetermined by the probe power ramping step which is either apre-configured parameter or broadcasted to the UE in PBCH/SBCH. The UEis allowed to perform re-transmission of probe request for certainnumber of attempts if the previous attempts resulted in no proberesponse from the eNB. Such maximum number of probe request attempts isgoverned by the parameter maximum number of probe transmission which iseither a pre-configured parameter or broadcasted to the UE in PBCH/SBCH.The probing procedure depicted in steps 403-405 can be either two stepprocedure or four step procedure. The details of two step probingprocedure and 4 step procedure are described in FIGS. 7, 8, 9 and 10.

At step 406, upon reception of the probe response the UE knows thesystem information (i.e. L1/L2 configuration or system informationblocks) related to each of the SCI value it acquired from PBCH/SBCH. TheUE applies and stores a set of system information parameters and theparameter values received in the probe response and tags the systeminformation parameter values with the associated SCI value(s). The proberesponse may comprise set of system information parameters andcorresponding parameter values associated with SCI other than the SCIbroadcasted by the camped cell. If the UE identifies set of systeminformation parameter values for SCI other than the SCI acquired fromcamped cell the UE stores the configuration parameters as aconfiguration list associated with the corresponding SCI.

At step 407 after applying the configuration the UE is able to performneighbor cell measurements to support an idle mode mobility. If the UEcontinues to stay in idle mode then the UE keeps tracking the DLcoverage beams for BRS_RSRP/BRS_RSRQ measurements of camped cell as wellas neighbor cell. Based on the cell re-selection criterion the UEperforms the idle mode mobility based on BRS measurements. During idlemode mobility if the UE acquires a new SCI value from the PBCH/SBCHtransmitted on a DL coverage beam and the UE does not know the meaningof the new SCI value then the UE needs to perform the probing procedureat step 408 if SCI value change is detected. If the UE detects that theconfiguration associated with new SCI value is available in storedsystem information then there is no need to perform the probingprocedure. It is possible that some SCI value(s) may change within thecoverage of the camped cell indicating that different L1/L2configuration is applied within the same cell coverage area.Traditionally, L1/L2 configuration is cell-specific so the SCI valuechange may occur when the UE performs cell re-selection. It may also bepossible that a cluster of cells may have the same SCI value meaningsame L1/L2 configuration. The various steps mentioned in FIG. 4illustrates the generalized probing procedure on the cell of 5G RAT onwhich the UE has camped; therefore either some of the steps can becombined, sequence of some steps can be modified or some steps can beomitted without deviating from the spirit of the illustrated procedure.The system information provided to the UE in the probe response or anyother message during the probing procedure is called System InformationTable (SIT) which specifies all parameter values that the range of SCIrefers to. For example typical broadcast information could easily cover100 parameters or more. Assuming the wireless operator want to be ableto use only one specific value for 99 of these parameters, and a rangeof 20 values for the 100th parameter then the range of SCI values wouldbe 20. Then it would be quite “stupid” to include in the SIT a full setof 100 parameters repeating twenty times, of which 99 parameters wouldbe identical and only one parameter would have a different value. Asmarter mechanism might be based on what could be called “multiplicationencoding”. E.g. assume the system information consists of 5 parameters:

ParamA: Has 10 values in standard, but operator only wants to use 2values: {a0, a1}

ParamB: Has 10 values in standard, but operator only wants to use 1value: {b0}

ParamC: Has 10 values in standard, and operator wants to use all: {c0,c1, . . . c9}

ParamD: Has 10 values in standard, but operator only wants to use 2values: {d0, d1}

ParamE: Has 10 values in standard, but operator only wants to use 2values: {e0, e1}

Let's assume the operator wants to be able to use any combination ofparameter values it intends to use in broadcast. Then the SCI could becomputed as follows:SCI=#valuenumberParamA*(#valuesParamB*#valuesParamC*#valuesParamD*#valuesParamE)+#valuenumberParamB*(#valuesParamC*#valuesParamD*#valuesParamE)+#valuenumberParamC*(#valuesParamD*#valuesParamE)+#valuenumberParamD*(#valuesParamE)+#valuenumberParamE

As an example, the SCI to indicate (a1,b0,c5,d0,e1) would be:

$\begin{matrix}{{SCI} = {{1*\left( {1*10*2*2} \right)} +}} \\{{0*\left( {10*2*2} \right)} +} \\{{5*\left( {2*2} \right)} +} \\{{0*(2)} +} \\{1} \\{= {40 + 0 + 20 + 0 + 1}} \\{= 61}\end{matrix}$

With this type of encoding, the SIT would just consist of a list of theparameter values that the operator intends to use. I.e. in the exampleabove, the SIT would indicate: {a0, a1}, {b0}, {c0, . . . c9}, {d0, d1},{e0, e1} as shown in Table 3 thus defining 80 SCI values.

TABLE 3 System Information Table Parameter A: {a0, a1} Parameter B: {b0}Parameter C: {c0, c1, . . . c9} Parameter D: {d0, d1} Parameter E: {e0,e1}

Potential drawbacks of the SCI encoding approach shown above are asfollows:

1) Only works if an SCI value is required for each combination ofparameter values. For e.g. does not result in optimal encoding if d0 isonly used in combination with e1 in the above example.

2) In case of extensions (additional parameters added by a certainfuture release of standard), all SCI values change. Then somehow it hasto be ensured that legacy UE still understand the SCI meaning for theparameters that are relevant for them.

An alternative solution could be to use explicit signaling for L1/L2configuration parameters (e.g. SCI #m: configuration of x, y, z . . . ;SCI #n: configuration of k, l, m . . . ) as shown in Table 4 below, andthen use multiplication encoding for some quite independent parametersthat are always valid and using a wide range of values. In suchalternative solution, the SIT comprises multiple blocks of systeminformation or multiple parts of system information. Each systeminformation block or system information part is identified by a uniqueidentifier so that UE can distinguish each system information block. Fore.g. System Information Block X (SIB X), System Information Block Y (SIBY), System Information Block Z (SIB Z) so on and so forth. There can beone or more configuration for each system information block/part whereineach configuration associated with a particular system informationblock/part is identified by a SCI. For e.g. System InformationBlock/Part X (SIB X) comprising parameter A, parameter B and parameter Chas three configurations namely Config 1, Config 2 and Config 3identified by SCI #1, SCI #2 and SC 1 #3 respectively. Eachconfiguration of SIB X takes different combination of values forparameters A, B and C. System Information Block/Part Y (SIB Y)comprising parameter D and parameter E also has three configurationsnamely Config 1, Config 2 and Config 3 identified by SCI #1, SCI #2 andSCI #3 respectively so on and so forth. Multiple configurations of eachsystem information block/part representing different combination ofparameter values along with the associated SCI are provided in the formof list. The list of configurations for the system informationblocks/parts is generically referred as System Information Table (SIT)in the present disclosure. The SIT is valid within the PLMN on which theUE has registered.

TABLE 4 System Information Table SCI#m: {a1, b0, c5, d0, e1} SCI#n: {a0,c5, d0, e1} SCI#o: {b0, c0, d1, e1} SCI#p: {. . . , . . . , . . . , . .. , . . .} SCI#q: {. . . , . . . , . . . , . . . , . . .} . . . SCI#z:{a1, b0, c0, d1, e0}

FIG. 5 is an illustration of generalized probe request and proberesponse procedure to acquire system information initiated by a UE whenpowered on and transitions to connected mode according to one embodimentof the present disclosure. All the steps from 501 to 506 are same assteps 401 to 406 of FIG. 4.

Referring to FIG. 5, at step 506 since the UE applied the configurationreceived in probe response so it can trigger the normal random access(RACH) procedure. All the parameters concerning the PRACH configurationare received in the probe response so at step 507 UE performs RACHprocedure on the camped cell of 5G RAT to establish RRC connection tostart DL/UL data exchange. The system information received in the proberesponse is sufficient to enable the UE to perform initial access andalso support idle mode mobility. In addition, the UE is not aware of thesystem information which is not covered/referred by the SCI value forwhich probe response was provided to UE. One example of suchconfiguration is the configuration required for supporting features likeMBMS, device-to-device (D2D) communication, wireless LAN (WLAN)interworking which can be provided with dedicated signaling after thenormal RACH procedure. However, the system information corresponding toother SCI values related to L1/L2 configuration applicable to coverageareas which are immediate neighbors of the cluster of TPs serving the UEis not known to the UE if not included in the probe response. Therefore,at step 508 after the UE successfully establishes the RRC connection,the eNB provides the UE additional system information in RRC message.This system information can be termed as system information table (SIT).The SIT has parameters and parameter values tagged with SCI values asshown in Table 3 or Table 4 which may be applicable to either theimmediate neighbors of the cluster of TPs serving the UE. The SIT may beapplicable to the entire coverage area of the operator network (i.e.PLMN) if a central node covers a very large coverage area controllingseveral hundreds to few thousands of TPs. The eNB can provide the SIT tothe UE through dedicated RRC signaling either in one shot or throughmultiple installments of system information corresponding to associateda plurality of SCI value(s). It can be also possible to broadcast theSIT if the eNB detects large number of UEs performing probing procedure.In addition to encodings shown in Table 3 and Table 4, one generalapproach would be to use some form of delta signaling when the SIT isprovided.

For example, eNB includes first SIT entry1 fully and for entry2 the SITsignaling only includes the delta compared to entry1, i.e. remove somefields/overwrite some fields. For entry3 the SIT signaling only includesthe delta compared to entry2 so on and so forth. An alternative would beto indicate for each entry a reference SIT entry, and then signal thedelta. In this case if the eNB knows the UE understands one SIT entry(e.g. the entry for the configuration provided in probe response, let'sassume SCI=17), then the SIT update table provided in dedicatedsignaling might not need any full entry. For e.g. entry 24: Referenceentry=17; Delta= . . . ; while entry 25: Reference entry=24; Delta= . .. and entry 26: Reference entry=17; Delta= . . .

At step 509, the UE stores the SIT in addition to the already receivedsystem configuration in probe response stored at step 506.

At step 510, the UE is in a position to start DL/UL data exchange withthe serving cell and able to perform mobility measurements. The firstlevel of UE mobility involves cell mobility where the serving cell of 5GRAT becomes weaker than a neighbor cell in which case a handover isneeded. In the present disclosure, the measurement event configured forthe UE for handling of cell level mobility of 5G RAT is based onRSRP/RSRQ measurements performed by the UE on beam-specific referencesignals (BRS) transmitted on the DL coverage beams by cells in thecoverage area. Such cell change procedure (i.e. handover) involvesreceiving RRC reconfiguration message containing the mobilityinformation wherein, UE re-establishes the user plane protocol stackincluding at least the MAC, RLC and PDCP entity after successful randomaccess on target cell. In such an event the UE re-establish the dataradio bearers on the target cell to continue DL/UL data transfer. Thesecond level of UE mobility is termed as beam level mobility wherein;the serving DL beam of the UE is switched or changed. Such beam levelmobility is directly handled at the physical layer or MAC layer by theconcerned serving cell of the 5G RAT serving the UE at that point oftime. Such beam level mobility is transparent to the UE and based on thebeam level measurement configuration provided to the UE after the UEsuccessfully complete random access and establishes RRC connection orRRC re-establishment. In an embodiment of the present disclosure, thebeam mobility measurement configuration includes the CSI-RS processesthe UE should monitor to perform CSI measurements that includes at leastCQI, RI, PMI, CSI-RS RSRP measurements on the CSI-RS resourcesconfigured for the UE. These CSI measurements are reported by the UE atphysical layer directly or MAC layer to the concerned serving cell sothat concerned cell takes beam mobility decisions.

At step 511 during cell level mobility or beam level mobility if the UEdetects the SCI value has changed in comparison to current active SCIvalue then the UE checks the stored SIT for the new SCI value. If thenew SCI value is not present in the stored SIT then the UE requestsupdate of SIT at step 512. Based on UE request for SIT update eNBprovides the UE with updated SIT at step 513.

FIG. 6 is an illustration of generalized probe request and proberesponse procedure to acquire system information initiated by a UE whenpowered on and transitions to connected mode according to anotherembodiment of the present disclosure.

Alternatively, as shown in FIG. 6 at step 611 eNB detects the UE isgoing to move in a mobility area either during cell level mobility orbeam level mobility where the UE does not have system informationconcerning the target mobility area. The eNB determines SIT update isneeded for the UE and at step 613 the eNB provides SIT update to the UEin RRC message. On providing the SIT for the first time and when the UEin RRC connected mode moves; the network maintains UE context and has anidea what SIT entries are provided to UE. So, if the RRC connected UE ismoving in an area for which it does not have entries then the networkprovides SIT update without UE request. The way today during X2handover, UE context is maintained so similarly SIT context can bemaintained by network to provide SIT update. Further on providing theSIT for the first time, when the UE receives the SIT it also receives avalidity timer associated with the SIT. Upon expiry of the timer the SITis considered invalid. If the UE performs power OFF and power ON afterreceiving the SIT and the SIT validity timer is running, there is noneed for the UE to perform probing procedure. The validity timer iseither applicable to all entries in the SIT or each entry has anassociated validity timer. Typical value of SIT validity timer is 24hours. UE may perform SIT update request if the SIT validity timer isabout to expire. The detailed UE behavior when there is change in systeminformation handling during idle mode and connected mode is describedlater in the present disclosure.

The various steps mentioned in FIGS. 5 and 6 illustrates the generalizedprobing procedure on the cell of 5G RAT on which the UE intends toestablish RRC connection; therefore either some of the steps can becombined, sequence of some steps can be modified or some steps can beomitted without deviating from the spirit of the illustrated procedure.

FIG. 7 is an illustration of two step probing procedure (700) based onprobe preamble transmission to acquire system information initiated by aUE when powered on according to one embodiment of the presentdisclosure.

Referring to FIG. 7, at step 701 the UE acquired the SCI from thePBCH/SBCH and determines to initiate probing procedure to understand themeaning of SCI. To initiate a probing procedure the UE needs to transmitthe probe request on a probe resource configured in the UL. The probesignal is based on preamble transmission to indicate probe request. Inan embodiment of the present disclosure, the probe signal is based onpreamble transmission to indicate probe request. In the probingconfiguration received in the PBCH/SBCH a set of root sequences isprovided based on which the UE derives plurality of preambles. This setof preamble can be used as probe signal to be transmitted on the proberesource to indicate probe request. This set of preamble can be furthergrouped in one or more mutually exclusive subset of preambles. Suchgrouping of preamble set is indicated with parameter probe preamblegroup sent in the probing configuration. The 5G wireless system isexpected to address different use cases having quite differentrequirements in terms of data rate, latency, mobility etc. However, itis expected the design of the air-interface of 5G would be flexible toserve the UEs having quite different capabilities depending on the usecase and market segment the UE cater service to the end customer.Therefore the 5G RAT operating on carrier frequency will be able toserve UEs having different UE capabilities. Such basic UE capability(i.e. eMBB UE, m-MTC UE, URLLC UE) can be mapped to the probe preamblegroup so that the UE chooses the probe preamble from the indicatedsubset and upon detection the eNB can determine the basic UE capability.In an embodiment of the present disclosure, there is one-to-one mappingbetween the set of probe preambles and the basic UE capability. Thisone-to-one mapping is either fixed in the standard specification oralternatively provided to the UE as part of the probing configurationindicated with parameter probe preamble group.

At step 702 the UE determines the probe resource for the transmission ofprobe preamble based on the probe offset starting from the start of thePBCH period (refer FIG. 3A). The probe offset can either be defaultoffset or indicated in the probing configuration. The probe resource isbasically a PRACH resource since a probe preamble will be transmitted onit as a probe signal. Therefore, the probe resource could also be usedas PRACH resource for the transmission of normal RACH preamble.Therefore, from system point of view the probe resource has dual usagein terms of probing procedure as well as random access procedure.

At step 703 based on the determined best DL beam index the UE selectsthe probe preamble from the subset of preambles depending on UEcapability. In an embodiment of the present disclosure, there isone-to-one mapping between the subset of probe preambles and the set ofDL coverage beams. This one-to-one mapping is either fixed in thestandard specification or alternatively provided to the UE as part ofthe probing configuration. The mapping of the probe preambles with UEcapability and DL beam index can be expressed in the form of matrix asshown in Table 5 below which can be indicated with parameter probepreamble group.

TABLE 5 Beam Index UE DL Capability DL Beam#1 DL Beam#2 DL Beam#3 . . .Beam#N eMBB UE Preamble#1 Preamble#2 Preamble#3 . . . Preamble#L MTC UEPreamble#L + 1 Preamble#L + 2 Preamble#L + 3 . . . Preamble#M URLL UEPreamble#M + 1 Preamble#M + 2 Preamble#M + 3 . . . Preamble#N

The UE transmits the selected probe preamble on the determined proberesource with a probe transmission power set according to the DLpathloss estimated from the received power measurement i.e. BRS_RSRP onbest DL beam index.

At step 703, the UE transmits the selected probe preamble on the firstprobe opportunity within the probe repetition period or UL beam sweepingperiod with the same transmission power. In an embodiment of the presentdisclosure, the probe transmission power is set according to the DLpathloss estimated from the received power measurement on best DL beamindex. In an embodiment of the present disclosure, the selected probepreamble is simply repeatedly transmitted or transmitted on different ULbeams corresponding to the probe time slot with the same transmissionpower covering the probe repetition period or the UL beam sweepingperiod. On completion of transmission of probe request during the proberepetition period or the UL beam sweeping period, the UE starts theprobe response window and starts monitoring the DL for reception ofprobe response.

At step 704, the eNB detects the transmitted probe preamble by the UEduring the probe repetition period or UL beam sweeping period. Since theone-to-one mapping between the set of probe preambles and the basic UEcapability is known to the eNB, the UE capability of the UE sending theprobe request is determined by the eNB. Further the eNB is aware of theone-to-one mapping between the subset of probe preambles and the set ofDL coverage beams, the best DL beam index is determined for thetransmission of probe response message. It may be possible one or moreTPs belonging to one or more eNBs to detect the probe preamble on theprobe resource at step 704 because same set of root sequence is used inneighboring nodes to derive a plurality of probe preambles. On detectingthe probe preamble one or more TPs belonging to one or more eNBsdetermine that there is a UE associated with a particular UE capabilityin its cell coverage area who has acquired SCI and wants to know themeaning of SCI.

At step 705, the eNB transmits on the cell served by the frequency theprobe response message addressed by the Probe-radio network temporaryidentifier (Pr-RNTI) in the beam specific search space to UE on the DLcoverage beam identified as best DL beam index. It may be possible atstep 705, one or more TPs belonging to one or more eNBs to transmit theprobe response which includes the system information (i.e. L1/L2configuration) associated with the SCI value which the responding nodestransmitted in the PBCH/SBCH. This may result in unnecessary responsesfrom neighboring nodes which detected the probe preamble in addition tothe probe response from the desired eNB. For the reception of proberesponse message since the UE determined the best (strongest) DL beamindex it would monitor the corresponding beam specific search space. Inan embodiment of the present disclosure, the probe response messageincludes at least one or more SCI value(s), preamble index, systemconfiguration associated with each SCI value and other configuration notcovered/referred by the SCI value. In an embodiment of the presentdisclosure, the probe response message is addressed by the Pr-RNTI inthe beam specific search space on the DL coverage beam identified asbest DL beam index. The responding eNB may repeat the probe response onthe best DL coverage beam determined at step 704. If the UE does notreceive the probe response while the probe response timer is runningthen the UE re-transmit the selected probe preamble upon expiry of thetimer.

However, the transmission power of the probe preamble is incremented bya power ramping step size. The UE is allowed to do such re-transmissionof probe preamble for pre-configured number of times with power rampingof preamble transmission power during each re-transmission attempt.

The various steps mentioned in FIG. 7 illustrates the two step probingprocedure on the cell of 5G RAT based on preamble transmission;therefore either some of the steps can be combined, sequence of somesteps can be modified or some steps can be omitted without deviatingfrom the spirit of the illustrated procedure.

FIG. 8 is an illustration of two step probing procedure (800) based onprobe ON/OFF signal transmission to acquire system information initiatedby a UE when powered on according to another embodiment of the presentdisclosure.

Referring to FIG. 8, at step 801 UE acquired the SCI from the PBCH/SBCHand determine to initiate probing procedure to understand the meaning ofSCI. To initiate probing procedure UE needs to transmit the proberequest on a probe resource configured in the UL. The probe signal isbased on an ON/OFF physical signal transmission to indicate proberequest. One example of design of such an ON/OFF physical signal issimilar to the scheduling request (SR) transmission in LTE. Since thesame ON/OFF signal will be used by UEs of different UE capability (eg.eMBB UE, m-MTC UE, URLL UE etc) different probe resources need to beprovided to differentiate the basic UE capability. A plurality of proberesources in time and/or frequency can be used to transmit the ON/OFFprobe signal to indicate different UE capabilities (refer FIG. 3B).There is one-to-one mapping between the probe resource and theassociated UE capability.

At step 802, the UE based on its UE capability determines the proberesource for the transmission of probe ON/OFF signal. The plurality ofprobe resources could be distributed either in time domain and/orfrequency domain and may be referred by a probe resource identifier(refer FIG. 3B). Such mapping of probe resources and the parametersprobe offset, probe slot period or probe slot offset are sent in theprobing configuration. Using the parameter probe offset starting fromthe start of the PBCH period and the parameter probe slot period orprobe slot offset (refer FIG. 3B) the UE determines the probe resourcebased on it UE capability. Further, it may be possible to map differentDL beam index to the probe resources in time domain and/or frequencydomain. The mapping of the probe resources with UE capability and DLbeam index can be expressed in the form of matrix of probe resourceidentifiers (Probe RID) as shown in Table 6 below which can be indicatedwith parameter probe resource Group.

TABLE 6 Beam Index UE DL Capability DL Beam#1 DL Beam#2 DL Beam#3 . . .Beam#N eMBB UE Probe RID#1 Probe RID#2 Probe RID#3 . . . Probe RID#L MTCUE Probe RID#L + 1 Probe RID#L + 2 Probe RID#L + 3 . . . Probe RID#MURLL UE Probe RID#M + 1 Probe RID#M + 2 Probe RID#M + 3 . . . ProbeRID#N

The probe resource is basically a resource on which the 5G eNB woulddetect energy reception. In an embodiment of the present disclosure,there is one-to-one mapping between the plurality of probe resources andthe basic UE capability. In another embodiment of the presentdisclosure, there is one-to-one mapping between the plurality of proberesources and the DL beam index. This one-to-one mapping is either fixedin the standard specification or alternatively provided to the UE aspart of the probing configuration indicated with parameter proberesource Group.

At step 803, UE transmits the probe ON/OFF signal on the first probeopportunity within the probe repetition period or UL beam sweepingperiod with the transmission power set according to the DL pathlossestimated from the received power measurement i.e. BRS_RSRP on best DLbeam index. Alternatively, in the probing procedure based on ON/OFFprobe signal the transmission power of the probe signal for the firsttransmission can be set according to the DL pathloss estimated from thereceived power measurement i.e. BRS_RSRP on best DL beam index plus afixed step size to ensure energy detection is feasible at eNB side.Unlike the preamble based probing where eNB has to detect the preamblein this procedure eNB has to just detect energy above a threshold on theprobe resource so probe re-transmissions may not be needed if the firsttransmission is done with sufficient power. On completion oftransmission of probe request during the probe repetition period or theUL beam sweeping period, the UE starts the probe response window andstarts monitoring the DL for reception of probe response.

At step 804, the eNB detects the transmitted probe signal by the UEduring the probe repetition period or UL beam sweeping period if thedetected energy is above a certain threshold. Since the one-to-onemapping between the plurality of probe resources and the basic UEcapability and DL beam index is known to the eNB, the UE capability ofthe UE sending the probe ON/OFF probe signal is determined by the eNB.It may be possible one or more TPs belonging to one or more eNBs detectthe energy above a threshold on the probe resource at step 804 becausethe same ON/OFF probe signal is used in neighboring nodes for proberequest. On energy detection above a threshold; one or more TPsbelonging to one or more eNBs determine that there is a UE associatedwith a particular UE capability in its cell coverage area who hasacquired SCI and wants to know the meaning of SCI.

At step 805, since the eNB knows the best DL beam index for the UE ittransmits the probe response on the corresponding DL coverage beam.However, if the probe resource mapping is done with respect to UEcapability only; then the eNB does not know the best DL beam index forthe UE and it transmits the probe response on all the DL coverage beamsin a sequential manner (i.e. DL beam sweeping is applied to the proberesponse). Since the UE determined the best (strongest) DL beam index itwould monitor the corresponding beam specific search space for thereception of probe response message addressed by the Pr-RNTI. It may bepossible at step 805, one or more TPs belonging to one or more eNBs DLbeam sweep the probe response which includes the system information(i.e. L1/L2 configuration) associated with the SCI value which theresponding nodes transmitted in the PBCH/SBCH. This may result inunnecessary responses from neighboring nodes which detected the energyabove a threshold. In an embodiment of the present disclosure, the proberesponse message includes at least one or more SCI value(s), proberesource identifier, system configuration associated with each SCI valueand other configuration not covered/referred by the SCI value. In anembodiment of the present disclosure, the probe response message isaddressed by the Pr-RNTI in each beam specific search space on thecorresponding DL coverage beam. If the UE does not receive the proberesponse while the probe response timer is running then the UEre-transmit the probe ON/OFF signal on the determined probe resourceupon expiry of the timer. However, the transmission power of the probeON/OFF signal is incremented by a power ramping step size. UE is allowedto do such re-transmission of probe ON/OFF signal for pre-configurednumber of times with power ramping during each re-transmission attempt.Regardless of the probing procedure of FIG. 7 or FIG. 8, the UEinitiated probing procedure is not subjected to contention resolutionunlike the random access procedure. This is because the outcome of theprobing procedure is acquisition of system information associated withone or more SCI value(s) acquired by the UE in a particular coveragearea from the PBCH/SBCH. Therefore, the probe response may be receivedby plurality of UEs within the particular coverage area regardless ofwhether the probe request was initiated by plurality of UEs or even ifinitiated the probe request may not have been detected by the respondingnode. Upon acquiring the system information associated with the acquiredSCI value if the UE desires to transition to connected mode then thenormal contention based random access procedure is followed by the UEbased on the applied system configuration.

The various steps mentioned in FIG. 8 illustrates the two step probingprocedure on the cell of 5G RAT based on ON/OFF signal transmission;therefore either some of the steps can be combined, sequence of somesteps can be modified or some steps can be omitted without deviatingfrom the spirit of the illustrated procedure.

FIG. 9 is an illustration of four step probing procedure based on probepreamble transmission to acquire system information initiated by a UEwhen powered on according to one embodiment of the present disclosure.

The drawback of the two step probing procedure is unnecessary responsesfrom more than one eNB detecting the probe request in addition to theprobe response from the desired eNB. Such unnecessary responses can beavoided with the four step probing procedure. Further, with thefour-step probing procedure it may be possible to indicate either thebasic UE capability or detailed UE capability to the network. It ispossible to combine the probing procedure and random access procedurewith the four step probing procedure based on preamble transmission.

At step 901 the UE acquires a plurality of SCI from the PBCH/SBCH anddetermines to initiate probing procedure to understand the meaning ofSCI. To initiate probing procedure the UE needs to transmit the probepreamble on a probe resource configured in the UL. In an embodiment ofthe present disclosure, the probe signal is based on preambletransmission to indicate probe request. In the probing configurationreceived in the PBCH/SBCH a set of root sequences is provided based onwhich the UE derives a plurality of preambles.

At step 902 the UE determines the probe resource for the transmission ofprobe preamble based on the probe offset starting from the start of thePBCH period (refer FIG. 3A). The probe resource is basically a PRACHresource since a probe preamble will be transmitted on it as a probesignal.

At step 903 based on the determined best DL beam index the UE selectsthe probe preamble from the plurality of derived preambles depending onthe best DL beam index determination. In an embodiment of the presentdisclosure, there is one-to-one mapping between the set of probepreambles and the set of DL coverage beams. This one-to-one mapping iseither fixed in the standard specification or alternatively provided tothe UE as part of the probing configuration. The UE transmits theselected probe preamble on the determined probe resource with a probetransmission power set according to the DL pathloss estimated from thereceived power measurement i.e. BRS_RSRP on best DL beam index.

At step 903, the UE transmits the selected probe preamble on the firstprobe opportunity within the probe repetition period or UL beam sweepingperiod with the same transmission power. In an embodiment of the presentdisclosure, the probe transmission power is set according to the DLpathloss estimated from the received power measurement on best DL beamindex. In an embodiment of the present disclosure, the selected probepreamble is simply repeatedly transmitted or transmitted on different ULbeams corresponding to the probe time slot with the same transmissionpower covering the probe repetition period or the UL beam sweepingperiod. In an embodiment of the present disclosure, during the proberepetition period UE repeats the transmission of selected probe preamblewith the same transmission power for plurality of probe time slots. Inanother embodiment of the present disclosure, UE may apply differentpre-coding for repetitive preamble transmission on each probe time slotof the UL beam sweeping period.

On completion of transmission of probe request during the proberepetition period or the UL beam sweeping period, the UE starts theprobe response window and starts monitoring the DL for reception of ULgrant. At step 904, the eNB detects the transmitted probe preamble bythe UE during the probe repetition period or UL beam sweeping period.Since the eNB is aware of the one-to-one mapping between the set ofprobe preambles and the set of DL coverage beams, the best DL beam indexis determined for the transmission of UL grant message. The probepreamble is only detected by the desired eNB because the set of rootsequences provided in the probing configuration from which the pluralityof probe preambles are derived are eNB specific. This avoids unnecessaryresponses from neighboring nodes where the root sequences are different,however within the desired node it may be possible that one or more TPsmay detect the probe preamble and respond to the UE. Since all the TPsof the desired node are controlled by a central node the UL grantmessage can be coordinated across the responding TPs.

At step 905, a coordinated response including at least the UL grant,detected preamble index, best UL beam index, UL timing advance, SFN (ifSFN is not transmitted in PBCH/SBCH) and PUSCH configuration is sent onthe best DL coverage beam determined by the responding TPs. In anembodiment of the present disclosure, the eNB determines the best ULbeam index based on the probe time slot in which the probe preamble wasdecoded if UL beam sweeping is applied. In an embodiment of the presentdisclosure, the UL grant message is addressed by the Pr-RNTI in the beamspecific search space on the DL coverage beam identified as best DL beamindex. The responding eNB may repeat the UL grant message on the best DLcoverage beam determined at step 904. At step 905, UE starts monitoringthe beam search space corresponding to the best DL beam index in orderto receive UL grant from concerned eNB of 5G RAT. On receiving thePDCCH/ePDCCH addressed by the Pr-RNTI in the beam specific search spacethe UE decodes the UL grant message from the concerned cell of the 5Gnode.

If the UE does not receive the UL grant message while the probe responsetimer is running then the UE re-transmit the selected probe preambleupon expiry of the timer. However, the transmission power of the probepreamble is incremented by a power ramping step size. The UE is allowedto do such re-transmission of probe preamble for pre-configured numberof times with power ramping of preamble transmission power during eachre-transmission attempt.

Based on the UL grant at step 905, the UE transmits a UL message on theindicated UL beam index based on the PUSCH configuration and UL timingadvance received in the UL grant message. If the best DL beam index asdetermined by the UE changes after the reception of UL grant messagethen the UE may include the new best DL beam index in UL message at step906. Else the same best DL beam index is included in UL message asindicated during the transmission of probe preamble. The UL messageincludes at least one or more SCI value(s) acquired from PBCH/SBCH, UEidentity, best DL beam index, Buffer Status Report (BSR) and basic UEcapability or detailed UE capability.

At step 907, the eNB detects plurality of SCI(s), UE identity and UEcapability sent in UL message by the UE. If multiple UEs transmit the ULmessage at step 906, then the eNB resolves the contention bytransmitting probe response at step 908 which includes the UE identitytransmitted by the UE in UL message. The probe response message includesa plurality of SCI value(s), the UE identity and the systemconfiguration associated with each SCI value and other configuration notcovered/referred by the SCI value. If at step 906, the UE transmits theUL message without the SCI then the eNB understands at step 907 theprocedure is a normal random access procedure. The UL grant message instep 905 may also be referred as a probe response message or a randomaccess response message. The probe response message in step 908 may alsobe referred as a contention resolution message. If the probing procedurein (900) is followed then a separate RACH procedure is not needed if theUE intends to establish RRC connection.

The various steps mentioned in FIG. 9 illustrates the four-step probingprocedure on the cell of 5G RAT based on preamble transmission;therefore either some of the steps can be combined, sequence of somesteps can be modified or some steps can be omitted without deviatingfrom the spirit of the illustrated procedure.

FIG. 10 is an illustration of four step probing procedure (1000) basedon probe ON/OFF signal transmission to acquire system informationinitiated by a UE when powered on according to another embodiment of thepresent disclosure.

The drawback of the two step probing procedure is unnecessary responsesfrom more than one eNB detecting the probe request in addition to theprobe response from the desired eNB. Such unnecessary responses can beavoided with the four step probing procedure.

Referring to FIG. 10, at step 1001 the UE acquires a plurality of SCI(s)from the PBCH/SBCH and determines to initiate probing procedure tounderstand the meaning of SCI. To initiate probing procedure UE needs totransmit the probe request on a probe resource configured in the UL. Theprobe signal is based on an ON/OFF physical signal transmission toindicate probe request. One example of design of such an ON/OFF physicalsignal is similar to the scheduling request (SR) transmission in LTE.Since the same ON/OFF signal will be used by UEs of different UEcapability (eg. eMBB UE, m-MTC UE, URLL UE etc) different proberesources need to be provided to differentiate the basic UE capability.A plurality of probe resources in time and/or frequency can be used totransmit the ON/OFF probe signal to indicate different UE capabilities(refer FIG. 3B). There is one-to-one mapping between the probe resourceand the associated UE capability.

At step 1002 the UE based on its UE capability determines the proberesource for the transmission of probe ON/OFF signal. The plurality ofprobe resources could be distributed either in time domain and/orfrequency domain and may be referred by a probe resource identifier(refer FIG. 3B for probe RID). Such mapping of probe resources and theparameters probe offset, probe slot period or probe slot offset are sentin the probing configuration. Using the parameter probe offset startingfrom the start of the PBCH period and the parameter probe slot period orprobe slot offset (refer FIG. 3B) the UE determines the probe resourcebased on it UE capability. The probe resource is basically a resource onwhich the eNB would detect energy reception. In an embodiment of thepresent disclosure, there is one-to-one mapping between the plurality ofprobe resources and the basic UE capability. This one-to-one mapping iseither fixed in the standard specification or alternatively provided tothe UE as part of the probing configuration.

At step 1003, the UE transmits the probe ON/OFF signal on the firstprobe opportunity within the probe repetition period or UL beam sweepingperiod with the transmission power set according to the DL pathlossestimated from the received power measurement i.e. BRS_RSRP on best DLbeam index. Alternatively, the determined transmission power isincremented by a fixed step size to ensure energy detection at the eNBin the first attempt itself. On completion of transmission of proberequest during the probe repetition period or the UL beam sweepingperiod, the UE starts the probe response window and starts monitoringthe DL for reception of UL grant.

At step 1004, the eNB detects the transmitted probe signal by the UEduring the probe repetition period or UL beam sweeping period if thedetected energy is above a certain threshold. Since the one-to-onemapping between the plurality of probe resources and the basic UEcapability is known to the eNB, the UE capability of the UE sending theprobe ON/OFF probe signal is determined by the eNB. It may be possibleone or more TPs belonging to one or more eNBs detect the energy above athreshold on the probe resource at step 1004 because the same ON/OFFprobe signal is used in neighboring nodes for probe request. On energydetection above a threshold; one or more TPs belonging to one or moreeNBs determine that there is a UE associated with a particular UEcapability in its cell coverage area who has acquired SCI and wants toknow the meaning of SCI. Even though unnecessary probe responses can beavoided but multiple nodes sending the UL grant message cannot beavoided. Since the UL grant comprises less information compared to theprobe response contents it is somewhat beneficial compared tounnecessary probe responses.

Since all the TPs of the desired node are controlled by a central nodethe UL grant message can be coordinated across the responding TPs. Atstep 1005, a coordinated response including at least the UL grant,detected probe resource id, PUSCH configuration, best UL beam index(optional) is sent on all the DL coverage beams (i.e. DL beam sweeping).In an embodiment of the present disclosure, the eNB determines the bestUL beam index based on the probe time slot in which the ON/OFF probesignal was detected above a threshold; if UL beam sweeping is applied.In an embodiment of the present disclosure, the UL grant message isaddressed by the Pr-RNTI in each beam specific search space associatedwith each DL coverage beam. At step 1005, UE starts monitoring the beamsearch space corresponding to the best DL beam index in order to receiveUL grant from concerned 5G eNB of 5G RAT. On receiving the PDCCH/ePDCCHaddressed by the Pr-RNTI in the beam specific search space the UEdecodes the UL grant message from the concerned cell of the node.

If the UE does not receive the UL grant message while the probe responsetimer is running then the UE re-transmit the ON/OFF probe signal uponexpiry of the timer. However, the transmission power of the probe signalis incremented by a power ramping step size. UE is allowed to do suchre-transmission of probe signal for pre-configured number of times withpower ramping during each re-transmission attempt. Based on the UL grantat step 1005, UE transmits UL message on the indicated UL beam indexbased on the PUSCH configuration received in the UL grant message. Sincethe best DL beam index is already determined by the UE then the UE mayinclude the best DL beam index in UL message at step 1006. The ULmessage includes at least a plurality of SCI value(s) acquired fromPBCH/SBCH and best DL beam index (optional).

At step 1007, the desired eNB detects one or more SCI value(s) sent inUL message by the UE. If the detected SCI value is different from theSCI value the 5G eNB is broadcasting in PBCH/SBCH then that node willnot send the probe response thus avoiding unnecessary probe responses.If multiple UEs transmit the UL message at step 1006, then it is not anissue because the eNB needs to detect at least one UL message with oneor more SCI value(s) to transmit the probe response at step 1008. Theprobe response message includes plurality of SCI value(s) and the systemconfiguration associated with each SCI value and other configuration notcovered/referred by the SCI value. The probe response message in step1008 may be transmitted on the best DL beam index or can be subjected toDL beam sweeping. If the probing procedure in (1000) is followed then aseparate RACH procedure is needed if the UE intends to establish RRCconnection.

The various steps mentioned in FIG. 10 illustrates the four-step probingprocedure on the cell of 5G RAT based on ON/OFF probe signaltransmission; therefore either some of the steps can be combined,sequence of some steps can be modified or some steps can be omittedwithout deviating from the spirit of the illustrated procedure.

FIGS. 11A and 11B are an illustration of scenarios concerning handlingof change in system configuration index (SCI) according to oneembodiment of the present disclosure.

Referring to FIG. 11A, scenarios concerning handling of change in systemconfiguration index (SCI) when the UE is either in idle mode mobility orconnected mode mobility are shown. As depicted in FIG. 11A, there is aplurality of cells of the 5G RAT (1110, 1120, so on and so forth) eachcontrolled by central node (referred as eNB). The coverage area of thecell served by carrier frequency of the 5G RAT may use a large number ofTPs controlled by the central node (i.e. eNB). Traditionally, the systemconfiguration is associated with a cell where the UE either uponhandover (in connected mode) or cell re-selection (in idle mode) acquirethe system information associated with the target (re-selected) cell.This traditional approach where system configuration is associated witha cell is depicted for Cell 2 (1120) where all the TPs within the cellcoverage area (1130 n) have the same system configuration i.e. L1/L2configuration (SCI #N). With this approach different cells can broadcastdifferent RACH configurations but the RACH configuration within the cellcoverage area (1120) is same. Assuming the applicability of cellspecific system configuration for the cell of 5G RAT then all TP's in acell have same system configuration (i.e. L1/L2 configuration). In suchscenario the change in cell area (handover/cell-reselection) is known tothe UE such that the PCI changes upon handover/cell-reselection andhence the associated SCI. However, one consequence of cell specificsystem configuration in the context of 5G cell is that all TP's willhave RACH at the same time. This will result in increase of RACH loadsupport at the eNB as depicted in Table 7. Assume one node with 500TP's. Further, assume RACH average load of X per second per TP, whichcan be handled with RACH occasions in one subframe. Also, assume RACHpeak load to be ten times of average load of X per second per TP. Thisthen results in the following:

TABLE 7 All TP's Cluster of All TP's have RACH 50 TP's have RACHoccasion have RACH occasion at in different occasion in same subframesubframes same subframe Average RACH load per 500 * X X 50 * X subframethat node has to be able to handle Peak load per subframe 500 * 10 * X =10 * X 50 * 10 * X = that node has to be able 5000 * X 500 * X to handleConsequence Expensive Cheap hardware hardware

However, in 5G wireless system this need not be strict restriction whereit is possible that several coverage area (1130 a, 1130 b, 1130 c so onand so forth) served by a different cluster of TPs within a cellcoverage area (1110) i.e. Cell 1 have different system configurationi.e. L1/L2 configuration (SCI #1. SC #2, SCI #3 so on and so forth). Oneadvantage is that within a cell coverage area (1110) different clusterof TP's (1130 a, 1130 b, 1130 c so on and so forth) can have a differentRACH configuration. This enables idle mode RACH load distribution forthe central node controlling one large cell (1120) handling large numberof TPs as depicted in Table 7. In connected mode for UE, the eNB canconfigure different RACH configurations for different UEs. For e.g. acell is supporting RACH access every 1 ms, but some UE's are given aconfiguration for t=0, 10 ms, 20 ms . . . and some other UE's for t=1,11, 21 ms, . . . This approach avoids having to reconfigure many UE's incase of UE mobility which would have been the case if the same RACHapplicable for entire cell is broadcasted and UE acquires theconfiguration in idle mode.

FIG. 11B is an illustration of fragmentation of the physical Cell-Id(PCI) into TP Group Id and TP-Id according to one embodiment of thepresent invention.

Referring to FIG. 11B, the “physical Cell Identifier” (PCI) isidentified by decoding the synchronization signal like PSS and SSS inLTE. The Cell-Id is frequency specific in LTE i.e. cells with sameidentifier on different carrier frequencies can be served from the sameeNB. The transmitted synchronization signals (i.e. PSS and SSS) arepre-defined unique sequences which upon decoding by the UE representsthe physical identity and physical identity group. The PSS uses threesequences for the physical identity while the SSS uses 168 sequences forthe physical identity group, which together determines one out of the504 physical cell identities (PCIs) represented by 9 bits. For RAT (5GRAT) similar approach can be considered wherein upon decoding thePSS/SSS the 9 bits of PCI/Cell-Id can be used to determine the TP-GroupId and the TP-Id. The TP-Id may be 3 bits, 4 bits, 5 bits or 6 bitsdepending upon the number of TPs within the TP-Group Id as depicted inFIG. 11B. The number of bits used for TP-Group Id and TP-Id providesflexibility to the network operator for supporting network deploymentwith different architecture options. The TP-Id size can be included inthe MIB broadcasted on PBCH. For eg. the parameter “TP-IdSize” can be2-bit indication in MIB broadcasted on PBCH which indicates the size ofthe TP-Id such that ‘00’ indicates TP-Id is 3-bits, ‘01’ indicates asTP-Id is 4-bits, ‘10’ indicates TP-Id is 5-bits and ‘11’ indicates TP-Idis 6-bits. The “TP-IdSize” parameter can also be just 1-bit indicationsuch that ‘0’ indicates TP-Id is either 3/4 bits and ‘1’ indicates TP-Idis 6/5 bits. Upon decoding the PCI/Cell-Id and determining the TP-Idsize after acquiring the MIB the UE can determine the TP-Id of the TP onwhich the UE decides to camp. The TP-Group Id is determined implicitlyfrom the remaining bits of PCI/Cell-Id after determining the TP-Id. Inan embodiment of the present disclosure, the Cell-Id/PCI is fragmentedinto TP-Group Id and TP-Id wherein the parameter TP-IdSize broadcastedon PBCH indicates the number of LSB bits used for the TP-Id.

The PCI/Cell-Id space of 9 bits based on 504 identities is taken as anexample to illustrate the fragmentation of PCI/Cell-Id into TP-Group Idand TP-Id and should not be considered as a limiting case. One advantageof the fragmentation of PCI/Cell-Id is that the UE can assume the systeminformation applicable for a newly detected TP on the serving frequencyafter decoding PSS/SSS is same if the TP-Group Id remains same as thatof the currently serving/camped TP. Network operator can plan orco-ordinate the configuration of system information to be same withinthe TP-Group Id. This means a cluster of TPs can be configured with thesame system information, for example, the RACH configuration, some L1/L2configuration, MIMO configuration can be same across the cluster of TPs.The TP-Group Id identifies such a cluster/group of TPs, wherein thecluster of TPs may belong to same eNB or may belong to different eNB. Ifthe TP-Group Id of the newly detected intra-frequency cell/TP remainssame then UE can assume the currently applied system information is alsoapplicable for the newly detected cell/TP. Such an approach offragmenting the PCI/Cell-Id into TP Group Id and TP-Id avoids therequirement for the UE to read the MIB i.e. PBCH for every newlydetected cell/TP or when UE changes the camped beam of the serving TPand hence useful for reducing the UE battery power consumption. In anembodiment of the present disclosure, the system information associatedwith one or more TP-Id(s) within the same TP-Group Id is same and UE isnot required to acquire system information for a newly detected TP-Id ifit belongs to the same TP-Group Id previously determined.

It can be possible to design the synchronization signals as combinationof PSS/SSS and beam index sequences. The beam index sequence can alsorepresent a 9 bit space which can be partitioned into “Beam Identifier”i.e. Beam-Id and “System Information Identifier” i.e. SI-Id. This couldbe fixed partition of 3 bits of MSB for “System Information Identifier”i.e. SI-Id and remaining 6 bits for Beam-Id. Alternately the 4 bits ofMSB can indicate the SI-Id while remaining 5 bits represents theBeam-Id. The SI-Id indicates the system information configurationapplicable in the detected cell/TP. The actual parameters for systeminformation are provided in one or more system information blocks whichcan be broadcasted or some of the blocks can be sent in UE dedicatedmanner. If a fixed partitioning approach is considered then the numberof bits for Beam-Id depends upon the maximum number of coverage beams tobe supported in the system. If a flexible partitioning approach isconsidered then the number of bits for Beam-Id can be indicated with aparameter “Beam-IdSize” in the MIB similar to the parameter “TP-IdSize”.

Upon acquiring the MIB and determining the TP-Id size and Beam-Id size(optionally), the UE is able to determine the TP-Id, the TP-Group Id,the Beam-Id and the SI-Id. If the SI-Id of the newly detectedintra-frequency cell/TP remains same then UE can assume the currentlyapplied system information is also applicable for the newly detectedcell/TP. If the SI-Id is indicated through synchronization signal likebeam index sequence then the system information can be different for thesame TP-Group Id. This means a cluster of TPs having the same systeminformation is independent of the TP-Group Id but linked to the SI-Id.The SI-Id identifies such a cluster/group of TPs having same systeminformation, wherein the cluster of TPs may belong to same eNB or maybelong to different e/NB. Therefore based on SI-Id indicated through thephysical layer signal like beam index sequence the UE is able todetermine whether system information needs to be re-acquired or not. Themain purpose of the synchronization signals like PSS/SSS and beam indexsequence is for downlink timing reference, subframe or radio frameboundary identification and additional scrambling of the physicalchannels such as LTE equivalent of PDCCH, PDSCH, PUSCH, PUCCH etc. Theidentity space provided by these sequences i.e. PSS/SSS and beam indexsequence is exploited for conveying one or more identities such asPCI/Cell-Id, TP-Id, TP-Group Id, Beam-Id, SI-Id etc required for theoverall system operation like cell detection, TP-Id switching, beamswitching and beam tracking, system information acquisition so on and soforth.

In the idle mode, UE monitors the DL coverage beams of camped cell andneighbor cell for cell re-selection. For change in SCI value the UE needto check the SCI before every paging reception and also before everymeasurement. (Change of SCI value means change of L1/L2 configuration orsystem configuration). In this alternative approach UE is required toread the MIB before every paging opportunity of the paging cycle. Thisapproach seems simple because UE can read the PBCH/SBCH every pagingcycle (assuming PBCH cycle is smaller than paging cycle). However, thiswould increase the UE idle mode power consumption (i.e. every pagingcycle the UE has to receive the paging message and the SCI value beforethat). Further, this also does not address the fact that the SCI mightalso span other information like neighbor frequency/cell informationwhich may be different in different parts of the cell. This would meanUE should then check before every measurement it performs what the SCIvalue is. Another third approach is whenever the UE changes DL coveragebeam (i.e. change of best DL beam index) in idle mode then it has tocheck for the new SCI value. As long as the UE is camping on the samebeam (i.e. same strongest PCI/cell id+beam id) it does not need to checkthe SCI value again unless it receives an indication in paging that theSCI value is changed. With this approach, the UE does not need to checkthe SCI value before every paging opportunity or before everymeasurement. As a consequence the battery power is not wasted. However,this approach may impose a restriction where different beams in a cellwhich are using the same beam index have to use the same SCI value.

In the connected mode, during beam level mobility the L1/L2configuration may change because different TP clusters use differentconfiguration. Since the beam level mobility is transparent to the UE,the UE can track only the DL coverage beams. Whenever the UE changes DLcoverage beam (i.e. change of best DL beam index), it has to check forthe new SCI value. The SCI value which is just an index indicated in thePBCH/SBCH such that UE after detecting change in SCI value looks intothe SIT and applies the configuration corresponding to the changed SCIvalue. UE autonomously releases the old configuration and apply the newconfiguration. Such autonomous reconfiguration by the UE does not leadto resetting of the layer 2 protocol stack. During the cell levelmobility in connected mode, UE receives the handover command from thesource cell. In such scenario it would be natural choice to use RRCsignaling for reconfiguration. Such an option is desirable for thestandalone mode where the RRC reconfiguration is directly coming fromthe 5G node.

FIGS. 12A and 12B are an illustration of operations at the UE side toacquire system information based on two step probing procedure accordingto one embodiment of the present disclosure.

Referring to FIGS. 12A and 12B, at step 1201, the UE powers ON and basedon the UE radio frequency (RF) capability, UE starts the cell search onthe minimum DL bandwidth on the frequency band supported by the UE.

At step 1202, the cell search operation involves detection ofsynchronization signal and subsequently detecting the beam indexsequence to determine the physical cell identity (PCI) of the detectedcell. Further, the UE determines the frame boundary and start of DLframe and determines the BRS resources based on PCI and detected beamindex sequence.

At step 1203, the UE starts measuring the BRS on the determined BRSresources and subsequently start to blindly decode the PBCH. On decodingthe PBCH UE acquires the MIB comprising at least: the DL systembandwidth. System Frame Number (SFN), Probing configuration, SBCHoffset. Subsequently, the UE decodes the SBCH to acquire plurality ofSCI. UE acquires at least: the primary PLMN. One or more systemconfiguration index (SCI), tracking area code (TAC), TP-IdSize andparameters for access control barring (ACB) from the SBCH. Based on theTP-IdSize, UE identifies the partitioning of the detected PCI/Cell-Idinto the TP Group-Id and TP-Id.

At step 1204, the UE initiates the probing procedure to know the meaningof SCI based on the probing configuration.

At step 1205, the UE determines the probe resource to transmit the proberequest signal. If the probe request is based on probe preamble then theUE selects the probe preamble based on UE capability and best DL beamindex. If the probe request is based on ON/OFF probe signal then the UEselects the probe resource based on the UE capability and best DL beamindex.

At step 1206, the UE transmits the probe request applying eitherrepetition or UL beamforming and starts the probe response window timerupon completing transmission of probe request. While the probe responsetimer is running UE monitors the DL in the beam specific search spacefor PDCCH/ePDCCH.

At step 1207, if the timer expires and there is no ePDCCH addressed byPr_RNTI to the UE then control goes to step 1208 else at step 1209 UEdecodes the probe response message addressed by the Pr_RNTI. The proberesponse message includes the system information (i.e. L1/L2configuration) corresponding to each SCI value and other configurationnot covered/referred by the SCI value which is applicable to coveragearea of the camped cell. The UE applies and stores the systemconfiguration received in probe response and at step 1210 decide eitherto transition to connected mode or continue in idle mode. The systeminformation (i.e. L1/L2 configuration) received in the probe response issufficient for the UE to initiate random access procedure. UEestablishes RRC connection by initiating random access procedure at step1211. On establishing RRC connection UE receives RRC message containingSIT, which the UE stores and start normal DL/UL data exchange with theeNB (103) at step 1212. During connected mode operation, the UE performshandover and beam switching based on its mobility and if the UE detectschange in SCI value for which corresponding system configuration is notpresent in SIT or if the SIT validity timer is about to expire then atstep 1213 UE requests SIT update from eNB (103).

At step 1208, when the UE does not receive probe response for a proberequested transmitted earlier then the UE increases the probe requestpower by a pre-defined step and re-transmit the probe request on theprobe resource such that control moves to step 1205. When the UE decideto remain in idle mode at step 1214, the UE performs BRS measurementsand idle mode procedures like monitoring paging and performing cellre-selection. During idle mode mobility if UE detects change in SCIvalue at step 1215, then the UE starts the probing procedure at step1205 to find meaning of the new SCI value if the UE does not have theSIT or the configuration associated with new SCI value is not present inthe stored SIT.

The various steps mentioned in FIGS. 12A and 12B illustrate the UEoperation to acquire system information based on two step probingprocedure; therefore either some of the steps can be combined, sequenceof some steps can be modified or some steps can be omitted withoutdeviating from the spirit of the illustrated UE operation.

FIG. 13 is an illustration of operations at the UE side to acquiresystem information based on four step probing procedure according to oneembodiment of the present disclosure.

The steps 1301 to 1304 are similar to steps 1201 to 1204.

Referring to FIG. 13, at step 1305, the UE determines the probe resourceto transmit the probe request signal. Since the probe request is basedon probe preamble, the UE selects the probe preamble based on best DLbeam index. The set of probe preambles is based on the root sequencereceived in the probing configuration acquired from MIB. Upontransmission of the probe preamble which is subjected to UL beamsweeping with a power level estimated from the DL pathloss encounteredon the best DL beam index, UE starts the probe response timer.

At step 1306, the UE starts monitoring the PDCCH/ePDCCH for UL grant.While the timer is running if the UE receives the UL grant addressed bythe Pr_RNTI then UE decodes the UL grant message which comprises atleast the UL grant, detected preamble index, best UL beam index, ULtiming advance, SFN (if SFN not transmitted in PBCH/SBCH) and PUSCHconfiguration. If the timer expires and the UE does not receive the ULgrant message then the UE increases the probe preamble power at step1308 and attempts a probe preamble re-transmission on probe resource atstep 1305. Based on the UL grant and indicated UL beam index, the UEtransmits the UL message comprising at least one or more SCI value(s)acquired from PBCH/SBCH, UE identity, best DL beam index, buffer statusreport (BSR) and basic UE capability or detailed UE capability at step1309. UE receives the probe response message at step 1310 which includesplurality of SCI value, system information associated with each SCIvalue and other configuration not covered/referred by the SCI value, UEidentity and UL grant.

If at step 1309, the SCI is not included in UL message then the proberesponse message is nothing but the contention resolution message fornormal random access procedure. On establishing RRC connection the UEreceives RRC message containing SIT and the associated SIT validitytimer, which the UE stores and start normal DL/UL data exchange with theeNB (103) at step 1311. During connected mode operation, the UE performshandover and beam switching based on its mobility and if UE detectschange in SCI value for which corresponding system configuration is notpresent in SIT or the SIT validity timer is about to expire then at step1312 the UE requests SIT update from the eNB (103).

The various steps mentioned in FIG. 13 illustrates the UE operation toacquire system information based on four step probing procedure;therefore either some of the steps can be combined, sequence of somesteps can be modified or some steps can be omitted without deviatingfrom the spirit of the illustrated UE operation.

FIG. 14 is an illustration of operations at the eNB to provision systeminformation based on probing procedure according to one embodiment ofthe present disclosure.

Referring to FIG. 14, at step 1401, the eNB (103) transmits in theminimum DL bandwidth the synchronization signal, PBCH, SBCH and BRSperiodically according to the PBCH cycle and SBCH cycle respectively.These signals are transmitted on plurality of DL fixed beams so that thesignals are available in the cell coverage area. The MIB is transmittedby eNB on the PBCH/SBCH which includes at least the DL system bandwidth,System frame number (SFN), primary PLMN, one or more systemconfiguration index (SCI), probing configuration, SBCH offset, trackingarea code (TAC), TP-IdSize and parameters for access control barring(ACB).

At step 1402, the eNB (103) detects the probe request signal on theprobe resource and determines that there is a UE in it's cell coveragewhich has acquired the SCI but does not know the meaning of the SCIvalue.

At step 1403, the eNB (103) determines the UE capability and best DLbeam index either based on the detected probe request or based on theprobe resource in which the probe request was detected. The eNB (103)transmits the probe response in the DL on the determined best DL beamaddressed by the Pr_RNTI in the beam specific search space comprising atleast plurality of SCI value(s), preamble index or probe resourceidentifier and the system configuration associated with each SCI valueand other configuration not covered/referred by the SCI value.

At steps 1404 to 1406, the eNB (103) upon detection of the random accesspreamble from a concerned UE completes the contention based RACHprocedure by resolving contention.

At step 1406, the eNB (103) transmits a dedicated RRC message to theconcerned UE containing the SIT and the associated SIT validity timer.Alternatively the SIT can also be broadcasted by the eNB (103). Duringconnected mode operation of the concerned UE, if the eNB (103) detectsthe UE has moved in a mobility area for which the UE does not have validsystem configuration or based on UE context knows the SIT validity timeris about to expire or on receiving a SIT update request from the UE thenthe eNB (103) sends a SIT update through dedicated RRC signaling to theconcerned UE.

The various steps mentioned in FIG. 14 illustrates the eNB operation toprovision system information based on the probing procedure; thereforeeither some of the steps can be combined, sequence of some steps can bemodified or some steps can be omitted without deviating from the spiritof the illustrated eNB operation.

FIG. 15A is a block diagram of 5G eNB depicting the hardware andsoftware modules for realizing the methods proposed in the presentdisclosure.

FIG. 15A is a block diagram illustrating various modules of a eNB;according to the embodiments of the present disclosure as disclosedherein. The primary blocks present in the eNB for communication with theUE include a communication module 1502, a control signaling module 1504,a processor module 1506, a memory module 1508 and a radio resourcemanagement module 1510.

In an embodiment of the present disclosure, the communication module1502 is configured to broadcast a synchronization signal, PBCH and SBCHto plurality of UEs. In another embodiment of the present disclosure,the communication module 1502 is configured to receive and detect aprobe request from plurality of UEs. In yet another embodiment of thepresent disclosure, the communication module 1502 is configured totransmit a probe response message to plurality of UEs. In an embodimentof the present disclosure, the communication module 1502 is configuredto communicate RRC signaling to and from the UE 102. For example, thecommunication module 1502 in a eNB 103 can be configured to communicatethe measurement configuration and RRC reconfiguration messagescomprising the system information table (SIT) to one or more UEs 102 a,102 b, 102 c. Further, the communication module 1502 in the eNB 103 canbe configured to transmit and receive data from one or more UEs 102 a,102 b, 102 c according to physical layer waveform and coding for awireless system.

The control signaling module 1504 in eNB 103 can be configured toprepare the related RRC messages to be transmitted to the UE and alsocan be configured to parse the related RRC message received from the UE.Further, the control signaling module 1504 in eNB 103 can be configuredto determine the bearer to be transmitted over within respective cellsin the eNB's. The bearer described herein can either be a data radiobearer (DRB) or a signaling radio bearer (SRB). The selection of abearer is based on several variables, which include for example, but arenot limited to, quality of service requirements (QoS), trafficcharacteristics of the bearer, and load and coverage area of the servingcell of eNB.

The processor module 1506 depicts a computing environment implementingthe method and system for system information acquisition by a UE in a 5Gwireless network, according to the embodiments of the present disclosureas disclosed herein. The computing environment of the processor module1506 comprises at least one processing unit that is equipped with acontrol unit and an arithmetic logic unit (ALU), a clock chip, pluralityof networking devices, and a plurality input output (I/O) devices. Theprocessor module 1506 is responsible for processing the instructions ofthe algorithm. The processing unit receives commands from the controlunit in order to perform its processing. Further, any logical andarithmetic operations involved in the execution of the instructions arecomputed with the help of the ALU. The overall computing environment canbe composed of multiple homogeneous or heterogeneous cores, multipleCPUs of different kinds, special media and other accelerators. Theprocessing unit is responsible for processing the instructions of thealgorithm. The algorithm comprising of instructions and codes requiredfor the implementation are stored in either the memory module 1508 orthe storage or both. At the time of execution, the instructions may befetched from the corresponding memory module 1508 or storage unit, andexecuted by the processing unit. The processing unit synchronizes theoperations and executes the instructions based on the timing signalsgenerated by the clock chip. The embodiments of the present disclosuredisclosed herein can be implemented through at least one softwareprogram running on at least one hardware device and performing networkmanagement functions to control the elements. The methods shown in theFIG. 14 include various units, blocks, modules, or steps described inrelation with methods, processes, algorithms, or systems of the presentdisclosure, which can be implemented using any general purpose processorand any combination of programming language, application, and embeddedprocessor.

Further, the memory module 1508 is also configured to store informationrelated to operation of the eNB 103 and the UE. The memory module 1508can be configured to store various UE related configurations when UE isin connected mode and UE capabilities for one or more UEs 102 a, 102 b,102 c etc.

The radio resource management module 1510 is responsible for variousaspects like beam level mobility and cell level mobility etc. The radioresource management module 1510 in the eNB 103 may be configured toevaluate the handover decisions based on the BRS measurement reportssent by one or more UEs. The eNB 103 receives the measurement reportsfrom one or more UEs 102 a, 102 b, 102 c etc and decide to performhandover for that particular UE. Similarly, the radio resourcemanagement module 1510 in the eNB 103 can be configured to receive theCSI-RS RSRP measurements for handling the measurement set and candidateset for beam level mobility handling for one or more UEs 102 a, 102 b,102 c etc.

FIG. 15B is a block diagram of UE depicting the hardware and softwaremodules for realizing the methods proposed in the present disclosure.

FIG. 15B is a block diagram illustrating various modules of a UE;according to the embodiments of the present disclosure as disclosedherein. The primary blocks present for communication include acommunication module 1512, a control signaling module 1514, a processormodule 1516, a memory module 1518, a radio resource management module1520 and a display module 1522.

In an embodiment of the present disclosure, the communication module1512 is configured to decode the synchronization signal, the beam indexsequence, PBCH and SBCH broadcasted by eNB. In another embodiment of thepresent disclosure, the communication module 1512 is configured totransmit a probe request signal on the probe resource. In yet anotherembodiment of the present disclosure, the communication module 1512 isconfigured to receive a probe response message transmitted by the eNB.In an embodiment of the present disclosure, the communication module1512 is configured to communicate RRC signaling to and from the eNB. Forexample, the wireless communication module 1512 in the UE 102 can beconfigured to communicate the request for SIT update, measurement reportand RRC reconfiguration complete message to the eNB. Further, thecommunication module 1512 in the UE 102 can perform random accessprocedure on the cell of the 5G RAT served by the eNB. Further, thecommunication module 1512 in the UE 102 can be configured to transmitand receive data from the eNB according to physical layer waveform andcoding assumed for 5G wireless system.

The control signaling module 1514 in the UE 102 can be configured toprepare the related RRC messages to be transmitted to the eNB and alsocan be configured to parse the related RRC message received from theeNB.

The processor module 1516 depicts a computing environment in the UE 102for implementing a method and system for system information acquisitionin a 5G wireless network, according to the embodiments of the presentdisclosure as disclosed herein. The computing environment of theprocessor module 1516 comprises at least one processing unit that isequipped with a control unit and an arithmetic logic unit (ALU), a clockchip, plurality of networking devices, and a plurality input output(I/O) devices. The processor module 1516 is responsible for processingthe instructions of the algorithm. The processing unit receives commandsfrom the control unit in order to perform its processing. Further, anylogical and arithmetic operations involved in the execution of theinstructions are computed with the help of the ALU. The overallcomputing environment can be composed of multiple homogeneous orheterogeneous cores, multiple CPUs of different kinds, special media andother accelerators. The processing unit is responsible for processingthe instructions of the algorithm. The algorithm comprising ofinstructions and codes required for the implementation are stored ineither the memory module 1518 or the storage or both. At the time ofexecution, the instructions may be fetched from the corresponding memorymodule 1518 or storage unit, and executed by the processing unit. Theprocessing unit synchronizes the operations and executes theinstructions based on the timing signals generated by the clock chip.The embodiments of the present disclosure disclosed herein can beimplemented through at least one software program running on at leastone hardware device and performing network management functions tocontrol the elements. The methods shown in the FIG. 12 and FIG. 13include various units, blocks, modules, or steps described in relationwith methods, processes, algorithms, or systems of the presentdisclosure, which can be implemented using any general purpose processorand any combination of programming language, application, and embeddedprocessor. Further, the memory module 1518 is also configured to storeinformation related to UE operation. The memory module 1518 can beconfigured to store various configurations like probing configuration,system configuration received in probe response, system informationtable (SIT), measurement configuration, etc received from the eNB.

The radio resource management module 1520 in the UE 102 is responsiblefor various aspects like cell level mobility and beam level mobilityetc. The radio resource management module 1520 in the UE 102 may beconfigured to evaluate the cell selection/re-selection handover eventsbased on the BRS measurements and perform CSI-RS RSRP measurementsrespectively.

The display module 1522 in the UE 102 can be configured so that user caninput information or information can output on the display for the userto understand some UE operations when the UE is operating in dualconnectivity mode of operation. Most of the UE operations aretransparent to the user and may not need user input nor output on thedisplay.

When the embodiments are implemented by software, firmware, middleware,or a microcode, a program code, or code segments, they can be stored ina machine-readable medium, such as a storage component. The code segmentmay indicate a procedure, a function, a sub program, a program, aroutine, a sub routine, a module, a software package, a class, or arandom combination of commands, data structures, or program descriptionsentences. The code segment may be coupled with another code segment ora hardware circuit by transmitting and/or receiving information, data,factors, parameters, or memory contents. The information, factors,parameters, and data may be transmitted using an arbitrary proper meansincluding memory sharing, message transmission, token transmission, andnetwork transmission.

In order to realize the software, the technologies described herein maybe implemented as modules (for example, processes, functions and thelike) performing the functions described herein. Software codes may bestored in memory units and executed by processors. The memory units maybe implemented inside or outside the processor. In this case, the memoryunits can be access the processor to be communicable through variousmeans known in the art. Although the present disclosure has beendescribed with an exemplary embodiment, various changes andmodifications may be suggested to one skilled in the art. It is intendedthat the present disclosure encompass such changes and modifications asfall within the scope of the appended claims.

What is claimed is:
 1. A method performed by a terminal in a wireless communication system, the method comprising: receiving, from a base station, master information block (MIB) including physical downlink control channel (PDCCH) configuration information associated with system information block (SIB) for an initial access and offset information associated with the SIB for the initial access, and receiving, from the base station, the SIB for an initial access based on the PDCCH configuration information and the offset information, the SIB for the initial access including: first information associated with one or more preambles, and second information associated with a physical random access channel (PRACH) resource; and third information associated with one or more SIBs set to be not broadcasted, selecting a preamble for a SI request based on the first information associated with the one or more preambles, wherein the preamble for the SI request is associated with at least one value identified based on the third information; transmitting, to the base station, the preamble for the SI request based on the second information associated with the PRACH resource; and receiving, from the base station, a response message associated with the preamble for the SI request, the response message including other SI, wherein the other SI includes SIB related to the at least one value, not received through the MIB and the SIB for the initial access.
 2. The method of claim 1, wherein the selecting of the preamble comprises: selecting a downlink beam based on a reference signal received power and a threshold; and selecting the preamble for the SI request based on the first information and the downlink beam, and wherein the threshold is configured in the SIB for the initial access.
 3. The method of claim 1, wherein the other SI includes at least one of: an SIB associated with an intra frequency cell reselection, an SIB associated with an inter frequency cell reselection, an SIB associated with an inter-radio access technology (RAT) cell reselection, an SIB associated with an earthquake and tsunami warning system (ETWS), an SIB associated with a commercial mobile alert system (CMAS), or an SIB associated with global positioning systems (GPS)/coordinated universal time (UTC) time.
 4. The method of claim 1, wherein the SIB related to the at least one value is different from SIB periodically broadcasted on a cell.
 5. A method performed by a base station in a wireless communication system, the method comprising: transmitting, to a terminal, master information block (MIB) including physical downlink control channel (PDCCH) configuration information associated with system information block (SIB) for an initial access and offset information associated with the SIB for the initial access, and transmitting, to the terminal, the SIB for an initial access based on the PDCCH configuration information and the offset information, the SIB for the initial access including: first information associated with one or more preambles, second information associated with a physical random access channel (PRACH) resource, and third information associated with one or more SIBs set to be not broadcasted; receiving, from the terminal, a preamble for a SI request based on the first information associated with the one or more preambles and the second information associated with the PRACH resource, the preamble for the SI request being associated with at least one value identified based on the third information; and transmitting, to the terminal, a response message associated with the preamble for the SI request, the response message including other SI, wherein the other SI includes SIB related to the at least one value, not received through the MIB and the SIB for the initial access.
 6. The method of claim 5, wherein the preamble for the SI request is selected based on the first information and a downlink beam, wherein the downlink beam is selected based on a reference signal received power and a threshold, and wherein the threshold is configured in the SIB for the initial access.
 7. The method of claim 5, wherein the other SI includes at least one of: an SIB associated with an intra frequency cell reselection, an SIB associated with an inter frequency cell reselection, an SIB associated with an inter-radio access technology (RAT) cell reselection, an SIB associated with an earthquake and tsunami warning system (ETWS), an SIB associated with a commercial mobile alert system (CMAS), or an SIB associated with global positioning systems (GPS)/coordinated universal time (UTC) time.
 8. The method of claim 5, wherein the SIB related to the at least one value is different from SIB periodically broadcasted on a cell.
 9. A terminal in a wireless communication system, the terminal comprising: a transceiver; and at least one processor configured to: receive, from a base station via the transceiver, master information block (MIB) including physical downlink control channel (PDCCH) configuration information associated with system information block (SIB) for an initial access and offset information associated with the SIB for the initial access, receive, from base station via the transceiver, the SIB for the initial access based on the PDCCH configuration information and the offset information, the SIB for the initial access including: first information associated with one or more preambles, second information associated with a physical random access channel (PRACH) resource, and third information associated with one or more SIBs set to be not broadcasted, select a preamble for a SI request, based on the first information associated with the one or more preambles, wherein the preamble for the SI request is associated with at least one value identified based on the third information, transmit, to the base station via the transceiver, the preamble for the SI request based on the second information associated with the PRACH resource, and receive, from the base station via the transceiver, a response message associated with the preamble for the SI request, the response message including other SI, wherein the other SI includes SIB related to the at least one value, not received through the MIB and the SIB for the initial access.
 10. The terminal of claim 9, wherein the at least one processor is, to select the preamble, configured to: select a downlink beam based on a reference signal received power and a threshold, and select the preamble for the SI request based on the first information and the downlink beam, and wherein the threshold is configured in the SIB for the initial access.
 11. The terminal of claim 9, wherein the other SI includes at least one of: an SIB associated with an intra frequency cell reselection, an SIB associated with an inter frequency cell reselection, an SIB associated with an inter-radio access technology (RAT) cell reselection, an SIB associated with an earthquake and tsunami warning system (ETWS), an SIB associated with a commercial mobile alert system (CMAS), or an SIB associated with global positioning systems (GPS)/coordinated universal time (UTC) time.
 12. The terminal of claim 9, wherein the SIB related to the at least one value is different from SIB periodically broadcasted on a cell.
 13. A base station in a wireless communication system, the base station comprising: a transceiver; and at least one processor configured to: transmit, to a terminal via the transceiver, master information block (MIB) including physical downlink control channel (PDCCH) configuration information associated with system information block (SIB) for an initial access and offset information associated with the SIB for the initial access, and transmit, to the terminal via the transceiver, the SIB for the initial access based on the PDCCH configuration information and the offset information, the SIB for the initial access including: first information associated with one or more preambles, second information associated with a physical random access channel (PRACH) resource, and third information associated with one or more SIBs set to be not broadcasted, receive, from the terminal via the transceiver, a preamble for a SI request based on the first information associated with the one or more preambles and the second information associated with the PRACH resource, the preamble for the SI request being associated with at least one value identified based on the third information, and transmit, to the terminal via the transceiver, a response message associated with the preamble for the SI request, the response message including other SI, wherein the other SI includes SIB related to the at least one value, not received through the MIB and the SIB for the initial access.
 14. The base station of claim 13, wherein the preamble for the SI request is selected based on the first information and a downlink beam, wherein the downlink beam is selected based on a reference signal received power and a threshold, and wherein the threshold is configured in the SIB for the initial access.
 15. The base station of claim 13, wherein the other SI includes at least one of: an SIB associated with an intra frequency cell reselection, an SIB associated with an inter frequency cell reselection, an SIB associated with an inter-radio access technology (RAT) cell reselection, an SIB associated with an earthquake and tsunami warning system (ETWS), an SIB associated with a commercial mobile alert system (CMAS), or an SIB associated with global positioning systems (GPS)/coordinated universal time (UTC) time.
 16. The base station of claim 13, wherein the SIB related to the at least one value is different from SIB periodically broadcasted on a cell. 